What Mosquitoes are in my Back Yard?


The mosquito larvae on these pages were gathered in Dora's backyard, at 1902 Metric, in the Villas on Walnut Creek apartment complex, on West Rundberg, near Rundberg and Metric.

What should I EXPECT to be in my back yard?

That could be summed up in three words.  "Don't even ask."

I got very tired of the media reports, based on last months' version of the CDC map, of probabilities that Aedes aegypti and Aedes albopictus might be in my part of the state/ country.   (The current version reports actual species found in isolated counties on a pathwork basis that happen to have done actual mosquito surveillance, and tells you specific species are actually in a few counties; one does not know if these species are in the counties they aren't mentioned as found in or there has been no surveillance, and usually there has been no surveillance.)  I've been tired of hearing which zip codes contain Culex mosquitoes that have west nile virus for a long time.  What a bunch of stupid, pathetic, idiots.   I decided to find out what mosquitoes are actually in my back yard, and document them.   

The recent maps of reported data on Aedes aegypti and Aedes albopictus, give the appearance that they do not exist in most of Texas, though they have consistently been found in Travis County for a long time.   The cooperative extension maps show a much better job of surveillance than what has come from the county health departments.  Even the cooperative extension maps would, for example, give one to believe that the common house mosquito, Culex quinquefasciatus (southern version of Culex pipiens), has NEVER been seen in half of the counties immediately around Austin, Texas, nor in most of northeastern Texas.   This is just complete irresponsibility in mosquito monitoring.   Obviously if they haven't found any southern Culex pipiens, they have no clue if Aedes aegypti and Aedes albopictus are there or not.    The Centers for Disease Control, which freely admits that far better monitoring needs to be done, until recently published maps that showed ranges of "likely" presence of these two mosquito apecies, and when people objected to that, they published a new map that shows where the mosquitoes have actually been found, specifically by county health departments, in isolated locations throughout the central southern states where the county health departments troubled to look for them, or else found them accidentally and cared enough to mention it in their reports.

Here are the Cooperative Extension maps of where their monitoring efforts have found Aedes mosquitoes.  They have actually done the best job of anyone of monitoring every sort of mosquito species.

The distribution of Aedes albopictus shown here suggests that the data may be out of date.  Aedes albopictus allegedly spread across the country from an import of infested tires in Houston in the mid 1980s.   

The map below makes it clear that Cooperative extension monitoring has large holes in it.  Culex Quinquefasciatus is the common house mosquito.   It is the southern variant of Culex pipiens, of West Nile virus fame.  This mosquito is found virtually everywhere throughout the United States.  There may be counties in western Texas that have only sporadic problems with mosquitoes, but in central and eastern Texas the notion that there are entire counties where this mosquito is not common is ludicrous.

The map below has to be my all time favorite, for idiocy.   It is based on "computer modeling".  Instead of going out and directly observing how many mosquitoes are in what location, or else shrugging and saying they can't or don't want to be bothered, they estimated how many mosquitoes there SHOULD be, based on temperature and rain conditions, for each month of the year, and for the full year.  So while I'm trapping about 2000 aedes aegypti and albopictus eggs a week in my back yard in Austin, San Antonio, the nearest place to Austin that is on the above map, is assigned a low probability for Aedes aegypti and Aedes albopictus.  


The map below is associated with Peter Zotek, some sort of mosquito head honcho in Houston, Texas.  Peter Zotek has done good work around Houston, but this map adds nothing to knowledge about what mosquitoes are in my backyard.   It was taken from an academic database of reports from assorted academic research, for Aedes aegypti.   This database specifically contained many reports for the Houston area, and several reports for the entire Austin area.   It gives Austin a high "likelihood of presence" of the Aedes aegypti mosquito.  Once again it doesn't actually tell me if the mosuito is in Austin or if so if it is in my back yard.  

Here are TWO sets of maps by the CDC, the old version and the improved version.

The shaded area represents the POTENTIAL RANGE of the two mosquito species.  It is based on reports of Aedes aegypti and Aedes albopictus incidentally submitted by county and city health departments around the country, to the CDC.  This was released at the end of March.  It changed over time.  This map is almost universally presented in the media as meaning that Aedes albopictus and aegypti might be in your area, might not.  

Then the CDC unsuccessfully tried to grow heads, and figured they'd better tell us where the mosquitoes actually ARE.   


This map shows counties where Aedes aegypti was reported between Jan. 1, 1995, and March 2016. Counties shown in yellow had records for one year within that time period; those shown in orange had two years of presence records, and those shown in red had three or more years of presence records.   Credited variously to the Entomological Society of America and the CDC.

It is hard to see, but the map actually shows Aedes mosquitoes reported in Travis County.   But, now, do the mosquitoes really know where the eastern and western county line is?  No, this is a map of where anyone has looked for them, and in Austin, UT has Aedes aegypti in its entomology collection from the early part of this century.  This map originally came from a source that collected data from academic as well as other sources.      According to an article in Science Daily, in June of 2016, "Researchers map mosquitoes that transmit Zika, Dengue by county", this map in fact comes from the Journal of Medical Entomology, not hardly from the CDC.  It "features maps of counties in the United States where these mosquitoes have been recorded, based on records from the Centers for Disease Control (local health departments), and Prevention ArboNET database, VectorMap, the poublished literature, a survey of mosquito control agencies, university researchers, and state and local health departments."  Then the CDC adopted the map and decided to tell us where Zika actually specifically is - which as one can see is next to nowhere.  

This is not a map of where Aedes aegypti actually is.   In fact, it creates as false an impression of where the mosquitoes actually are as the other maps do.  This is based on mostly sporadic reports of Aedes aegypti by county and city health deparments.  Very few health departments around the country systematically monitor Aedes species, most of those that do are in Houston, Florida, Nevada and California, and the traps routinely set out for Culex are NOT very good at catching Aedes, particularly Aedes aegypti.   This map is based on data so nonexistent it's a terrible joke.  Fortunately, I found just one single article, by NPR, that took even a good enough look at it to draw the conclusion that very few places in the U.S. have anything to worry about from Aedes aegypti.  Their interpretation:  "Here's Really Where Zika Mosquitoes Are Likely In The U.S.", followed by the above map.  Half of the article's readers managed to tear NPR's conclusions about where Aedes aegypti is not apart in the comments, because they were able to see, partly from the fine print in the last four paragraphs, that the map is based largely on the fact that the data doesn't exist, but NPR, that self-alleged model of responsible reporting, never retracted it.     

It is also clear that the CDC has made no effort to utilize Cooperative Extension and academic data, just their own hapless, virtually useless health department system.

In fact, neither academic efforts, nor the Cooperative Extension system, nor the CDC, have made any use whatever of each others' data.

Notice that once again, Travis County is orange, but local media have reported only the "chance of being in range" CDC map.

The local university entomologist who has helped me learn how to identify mosquitoes, told me a friend of his wrote an article,  "Predicting the distribution of Sasquatch in western North America: anything goes with ecological niche modeling" and created this map:

The map is based on reported Bigfoot sightings and reported Bigfoot footprints.

So we end up with a complete probablistic map of where one can expect to find Bigfoot.  This means, if you go to the mountains east of Los Angeles, you are very likely to run into Bigfoot, but, he might be in your back yard, or he might not!   

The lack of responsible monitoring by public agencies in most of the country, has led to the U.S. Department of Agriculture, with the CDC, to run a citizen science program, to encourage citizens, especially students, to monitor for mosquitoes in various ways, and report what they find.  One can use local resources to help with identifying the mosquitoes, or submit specimens to the USDA.  See "Uncle Sam wants you to fight Zika" article in the resources below.


What is actually in my backyard


Three guesses and the first two don't count.  

My project is the sort of mosquito eggs and larvae monitoring project that anyone can do very easily.   

I initially gathered some of my mosquito larvae, from a permanent standing water hole under a bridge that crosses God knows what on Rundberg.   When it rains, water flows on down the drainage ditch that is otherwise called part of Walnut Creek, to vanish underground at another bridge for a driveway, and flow into the actual beginning of Little Walnut Creek.  At the head of the actual beginning of Little Walnut Creek is a small but deep and permanent water collection pond, near 183 and Metric.   Lord only knows where the water that feeds Little Walnut Creek itself or the water hole under the bridge on Rundberg comes from.   This bridge and pool of water are located where you see the little square blue bus stop sign on Rundberg.

Here is what it looks like when it rains hard, but that does not happen very often.  (And the "creek" does not outlast the rainstorm.)  The buckets were collecting rainwater for the mosquitoes.  The chairs were stopping the buckets from blowing into rushing water - one of my five gallon aquarium cleaning buckets was already gone.

I gathered mosquito larvae from the water hole above, and from my experimental Aedes larva trap.   They strongly appear to be the same type of mosquitoes; their features look alike.   

The local health department vector control unit came and put bacterial mosquito larva killing dunks in the "pond".

The point of displaying the photo of what happens when it rains, is that not only does the standing pool obviously overflow with all of its contents, as well as any eggs Aedes mosquitoes may have laid above the water line, but the water flows very forcefully.  It all ends up in a water collection pond on the other side of the fence from the apartment complex, which is kept stocked with fish to eat mosquitoes there, and those fish would die if something happened to the mosquitoes.   That catchment pond forms the head of a major branch of Little Walnut Creek.   The health department specifically treated the pond with a dunk that contains bacteria that destroy mosquito larvae.  It sounds like a good idea - until it escapes.   Chemical insecticides would not work better.  And the city has not responded yet to the fact that the department allegedly reported the mysterious pool of water to the streets department.  

Here are photos of my Aedes collection experiment.  

I got the idea for a tire trap from the recently publicized work of a Canadian researcher who did a small pilot project in South America.  Here are his instructions for making an ovillantra, but his process doesn't actually work well for a ghetto resident like myself lacking in resources; noone in my environment has large drills or table saws capable of cutting through tires.   I had to go with simply hanging up the tire and putting the ingredients in it - and cleaning it out with an aquarium net, instead of draining and straining the water and putting it back.   He also recommends some kind of special paper that he doesn't even specify what it is, that comes with a kit that the company that sells his factory made mosquito larva traps, probably wants to market to the third world, I'm guessing for the $4 he says his method costs.   

The ovillanta trap was originally developed to combat West Nile virus in Northern Ontario, and proved very effective in that context, so it is possible that the device is as likely to attract Culex mosquitoes (that carry West Nile Virus) as Aedes mosquitoes that carry dengue and zika.  The idea was that you get the mosquitoes to lay eggs where you want them to, and then you kill the eggs and larva and dispose of them, so they never become mosqitoes.   It also proved effective at dramatically locally reducing numbers of Aedes mosquitoes in the community in South America.   Studies consistently find that if old tires are present, Aedes will lay a third of all of their eggs in them.   Culex allegedly prefers small open bodies of water full of stinking, rotten vegation.   

I provided disks cut from foam dinner plates and blue plastic dinner plates, topped with paper towel, and also an old piece of brick, for the mosquitoes to sit on to lay their eggs.  Since nothing happened for nearly two weeks until it actually rained, I'm wondering if they actually laid their eggs on the walls of the tires out of the water.  

It is important to reuse the water, because mosquitoes lay eggs where other mosquitoes have previously laid eggs; they leave pheromones behind so other mosquitoes will know eggs have been laid here.  This communicates to the mosquitoes that this is a good place to lay eggs.

Two things that have me wondering are that Culex lays its eggs directly in the water, and the eggs form visible floating rafts of stuck together eggs, and I never saw any such rafts.   Aedes, on the other hand, lays eggs on damp dirt where there will be water when it rains (and in the laboratory on damp paper towels) - and the eggs may or may not need to actually dry out before they will ever hatch.   Aedes also likes to lay eggs on the sides of containers that will contain more water when it rains.   My tire was full to overflowing after it rained; I only put the recommended 2 liters of water in it.   

I also put out a clear plastic container with rocks and plastic floats in it, a potato chip wrapper with water in it, a bottle cap that I kept a small amount of water in, and a clear plastic bottle with water in it; and outside under a tree, I had an open bucket of rainwater, and an old black plant pot inside a bigger container with water in them.   They did not, to be sure, remain free of caterpillars from the tree, other larva, and the bodies of beetles.   

I used collected rainwater in all of these containers.  I added two or three dead leaves to each; four in the tire, a couple of grains of wheat, and a small pinch each of yeast and spirulina.   Both Aedes, which likes clean water that contains dead leaves, and Culex, which loves stinking pools of water full of rotten vegetation, lay eggs where the young can count on having plenty of microscopic life to eat.  (If you put in too much food for the protozoa the water will go bad, which might excite Culex mosquitoes but not Aedes).

I also have plastic covers secured to cover my traps if it seriously pours rain.  

Two days after the rainstorm, I found both the tire and the water hole full of mosquito larvae.   The bucket, pot, potato chip wrapper, bottle and bottle top didn't contain a single mosquito larva.   

I tried paper towel on the square blue plastic dish, but wouldn't know if anything laid eggs there.  One should also know that my landlord has a considerable amount of junk on the back porch that collects water when it rains (and then I go out and dump the water), and Aedes could be laying eggs on it.   Aedes is bright enough to mosquito little know that water has been there and will be there again - probably from the biolife.   Some neighbors have their own little "science experiment" going on their back porch, in the form of a big old bucket that just sits there, with junk in it.

I used 40 x power on my microscope and my cell phone to get the following pictures.  This tactic captured body parts of the mosquito larvae, and I seem to be deficient in clear photos of the appendages on their faces.   These would be longer in Culex than in Aedes mosquitoes.   However, Aedes mosquitoes have much, much shorter hind end sections than does Culex.   These hind ends are all Culex.   I think so are the face appendages.   The hind end parts also have hairs that are lacking with Aedes.

Behaviorwise, the larvae from both places hung at 45 degree angles from the surface of the water.   This is typical of both Culex and Aedes, but not, for instance, of Anapholis (which carries malaria, when there is any malaria around for them to carry; it's been eradicated from North America).   They did this funny lengthwise somersault thing getting from the bottom of the container to the surface of the water.   The water hole had some larvae that were bigger and darker, and far better at hiding to get away from my water dropper, than the others, but under the microscope they looked identical.  They were probably just older.   

The photo on top is of larvae from the tire, and on the bottom of larvae from the water hole.   \

Over time my setup evolved.  It seems Aedes may actually prefer contaminated brown water, so I put in more leaves than previously.  24 hours later there are already dead black flies floating in it...   A mosquito expert suggested to me that flat wooden wood pieces wrapped in damp paper towel may work better than floating paper towel on top of something, even though usually those were damp.  I put varying amounts of dead leaves, many of them found under rain spouts, a couple of spelt berries, a little brewers yeast and spirulina powder, in each tire.   The leaves and spelt berries, and probably the yeast and spirulina, feed microorganisms that are actually what the mosquito larvae eat, which is why mosquitoes want to lay eggs where there is organic matter.  I varied the size of the tire and the depth of the water, as well.

Here is my lab.  The microscope below is my university grade 40x to 900x with oil immersion microscope.  500x is actually needed to clearly see the shape on mosquito scales to distinguish Aedes aegypti and Aedes albopictus larvae.   

I bought an old low power microscope on Craigslist - 25x to 100x.   I also tried out photographing through magnifying lenses with my cell phone.  I had to make an adjustment on the microscope to expand my field of vision; it would have helped on the bigger microscope as well.

The toilet paper roll, with a small amount cut off of one end, holds the cell phone camera off the lense a little bit.  

Eventually I made more upgrades to my equipment.

I made another upgrade in my equipment, and looked at one of my mosquitoes under the low power microscope.  

The Gosky universal cell phone adapter mount.  It even comes with a blue tooth camera button, that works with recent OS's or with a particular app if the capability didn't come with the OS.   Or it comes without the button, as the Gosky Universal Cell Phone Adapter Mount, for $3 less.  I bought it on Amazon.  I found a large number of such devices available; evidently it is becoming common to take photos through a microscope with a cell phone.  Alex Wild told me that because phone cameras are increasingly good cameras, that is becoming a viable option.   In fact, my cell phone has twice the resolution as my old Kodak digital camera that took acceptable photos through a microscope.

The rubber band is on my phone for traction; it has nothing to do with the cell phone holder, nor with the phone.

You will notice that my optics just don't seem to be the greatest.   I asked Alex Wild for help.  On the high quality but low power dissecting microscopes in the UT entomology collection lab, I get clear sharp photos, with my phone.  

Alex Wild is a professonal photographer, did his PhD. post dissertation (whatever that means) on photographing insects, teaches classes on the subject, in Austin and around the Americas, and gave a paper about it at a recent international entomology conference.   He has an expensive, multiple thousand dollar professional setup in his lab as well as at home for microscopic photography of insects - though it won't do 500x.   

Here are his web sites.   

Myrmecos  his personal blog.  There's a beatiful photo of a Culex mosquito emerging from its pupa here.   

Alex Wild:  The Diversity of Insects

Here is his discussion of how to improve the contrast on a microscope photograph of a midge, which is closely related to mosquitoes and looks very similar.

Insects Unlocked project

More on Insects Unlocked

Twitter page of Insects Unlocked - looks like photos posted regularly

Alex Wild's photography setup

Instead of a web site, Insects Unlocked has a Twitter account and a Flicker account.  

He's always looking for volunteer help at the UT Entomology Collection that he heads.   One might work on labeling the main collection, which Alex just took over, or help with projects that are associated with the lab, like Ian Wright's lizard diet study, which is part of a massive TPWD funded project to learn more about an endangered lizard.   I now work on this project, and I took theers working on it.   The lizard eats a diet entirely of bugs, and this is a survey of what bugs are found in its environment.  

Alex helped me play with photographing my mosquitoes with my phone.   He thinks the issue is the optics on the inexpensive microscope, even though it looks like a microscope that should have good optics.  It was acquired from a coin collector or seller, and met his requirements very well!    

Auditors are also invited to unofficially audit the introductory entomology class.  It includes a broad introduction to insect biology, and basic how to key them, with a laboratory insect collecting and identification project, and an optional project such as monitoring mosquitoes.  

After working with my mosquito larvae, of course I killed them before disposing of them.  I boiled them for a few minutes.  Even the ones I looked at, that I immobilized using bug spray.  Them critters is known to be hard to kill!

I upgraded my equipment again.

AmScope LED-64-ZK Microscope Ring Light with Adapter

Then I moved my lab into my air conditioned bedroom/ office because it has gotten too hot and muggy to work in the house.  The ladder leads to my loft bed above my desk.  

Go to my page on Culex and Aedes aegypti larvae identified at my house at Metric and Rundberg, Austin, Texas, late spring, 2016, for detailed information with detailed illustrations on identifying the larvae of Culex quinquefasciatus and close relatives, Aedes aegypti and Aedes albopictus.   

I identified Aedes aegypti larvae and Culex quinquefasciatus larvae.   



While figuring out how to identify them, I took my larvae and some pupae out to Alex Wild, an entomologist at UT Austin.   An adult of the Culex lot above unfortunately lost half its tufts of hair by the time he got a chance to look at it, and couldn't be keyed.   Under the laboratory dissecting microscope, the Aedes larva looked far clearer.  Bright electric light helps.  We couldn't get our cell phones to line up suitably for taking photos.  However, the larva had a nice ventral tuft on its anal segment, with five or six hairs.   It had definite vivid hooks attaching its thorax tufts.   On the comb scales the magnification wasn't quite up to the task, but we could just make out what appeared to be little spicules on each side of the bulge on the comb scales.   Dr. Wild said that he has had far more luck finding adult Aedes aegypti around Austin than Aedes albopictus, especially in his own garage in west central Austin.   

Since then, both Alex Wild, and Elizabeth Brown of the Travis County Cooperative Extension, have been able to examine adult mosquitoes that emerged from the pupas and larvae that I took them, and both confirmed that these are Aedes aegypti.

Adult Aedes Aegypti

It is actually takes far longer to identify mosquito larvae, then makes any sense if one wants to monitor what mosquitoes are in a location over time.   It is far easier to either trap adults, or raise the eggs and larvae from ovatraps and then identify the adults.   So I moved to rearing my mosquitoes.

I used pint (close to 500 ml) plastic containers with lots of holes punched in the lids with a thumbtack.   I often put a piece of leaf or two in the container for protozoa to grow around.   I fed ground fishfood and powdered spirulina.   It turns out that Aedes aegypt and albopictus vary in their diet; one prefers an animal based diet and the other prefers a vegetable based diet.   The two species are competitive, and compete with Culex mosquitoes in containers, so it is important to make sure they have plenty of their assorted diet and are sorted by size of larvae, and genus if possible.  Typically Aedes larvae are faster growing and greener, and feistier, than Culex larvae.   It is important to try not to overfeed.   It is important to check their containers every day, both to move pupae to separate containers, and to change their water if it has gotten cloudy or smelly.   Their water needs to be dechlorinated tap water or else bottled spring water.   (Unlike the water in traps which needs to be rain water, spring or stream water, or bottled spring water.)

Initially I chilled the mosquitoes until they couldn't fly, about 40 minutes, then picked the adult mosquitoes from among the larvae with tweezers, and put them in a container with a cover over it, because they would soon recover and start flying around.  This didn't work at all on Aedes aegypti because they take about thirty seconds to recover, and mosquitoes were getting loose, and also my larvae were getting injured by the cold.   So I began moving pupae to separate containers, and when they were all adults I made little slits in the lids and turned the containers on their sides in the sink, so that the water drained out, and then put the containers in the freezer overnight, or until I could sort them.

Culex mosquitoes were easily separated out by their slim bodies and golden color.   Neither I nor Alex Wild have the skill level to separate Culex mosquitoes by species.  I suspect that I have several species.  They carry the same diseases, especially west nile virus, so often there is no effort to separate them by species.   The differences are small differences in color (which varies completely within species in any case), pattern on abdomen, vertical striping on legs that are usually vertically bicolored with a bit of a gradient (so hard to tell the difference), little hard to discern white spots on the back of the thorax, and striping on the palps.   



You can just make out the white tip on its palp, and the circular band around the back of its thorax.  

This view catches the white bands at the joints in its legs.  You can also see the general glittery appearance of the thorax I am told is characteristic of Aedes.

Here are the legs in more detail.

I think I may have looked at both a male mosquito and a female mosquito.  Here is a closeup of the front parts.  

Yup, male and female.  (Photo found online)

The male has very long palps, while the female has the characteristic short white-tipped palps.  In fact, it rather looks as though Anopheles, which breeds in marshes and carries malaria, differs from other mosquitoes in that the females share long palps with the males.  

"As is usual in mosquitoes the male [A. aegypti] is distinguished from the female by the plumose antennae and the longer and more developed palps, which in the male are about as long as the proboscis, whilst in the female they are only about one-quarter as long."  (Sir S. Rickard Chrisotphers, Aedes Aegypti (L.): The Yellow Fever Mosquito, Google books)

This photo from the web shows the classic lyre shape of the white mark on the abdomen, but it's hard to see properly in a typical side view.  


Both Aedes aegypti and albopictus in my back yard


Then I began looking through my little bucket of freeze dried mosquitoes, that grew from the larvae in my egg traps.

For a good two weeks, I have consistently found larvae but few or no eggs in the bicycle tire full of leaves and flowers, two or three larvae but lots of eggs laid on the paper in both of the large regular tires that have a few leaves and a couple of spelt grains in them, and any bug larvae but mosquito in the large wide tire with a small amount of larva and rocks in it along with vegetation.  So most of my larvae came from the bicycle tire.   

I found slightly more Aedes albopictus than aegypti.

I am wondering if the relatively cool and rainy weather also changed the ratio of mosquitoes in my egg traps to favor albopictus.  

Online images:

Of course, both have the white bands on their legs, and the general silvery speckled appearance.

The first is Aedes albopictus, the Asian tiger mosquito, the second is Aedes aegypti, the yellow fever mosquito.   Aedes aegypti came to this country on slave ships from Africa, and the Asian tiger mosquito came here in the 1980s in shipments, especially of used tires, from overseas.  Both carry dengue, and both carry Zika.   (There was an actual island epidemic in the Pacific where Aedes albopictus is known to have been the carrier.)   Neither carries any virus unless the illness as well as the mosquitoes is established beyond a certain very low level.  Aedes aegypti is dependent on humans for both blood and places to breed, and doesn't fly well enough to be found more than 500 feet from human habitat, while albopictus will bite other animals and breeds in both manmade containers and tree holes.  Usually one species or the other is found to dominate in any location, with aegypti dominant in cities and albopictus dominant in suburbs and rural areas, across the southern zone where both mosquitoes occur, but both mosquitoes are being found in the same locations around Austin.   The strain of albopictus common in the U.S. came from a temperate part of eastern Europe, and thrives throughout the U.S., with eggs able to withstand freezing, while  Aedes aegypti is a strictly tropical mosquito that doesn't thrive outside of a subtropical climate.   Such a climate is found across the southern U.S., and halfway up both coasts, and urban areas create better habitat for aegypti overwintering than more rural places.  These mosquitoes spend a lot of time and often lay eggs inside buildings, and the eggs live up to a year in a dried state; they can also overwinter in plant saucers and so forth that were brought in for the winter.  The same genetic strains of the virus continue in the same neighborhoods from year to year.  In the summer, the climate of New York state is subtropical, because of the gulf stream.  Yellow fever, which is closely related to the dengue and zika viruses, was a problem even in downstate New York in the 18th and 19th centuries, as far north as Albany.  It broke out in New York and moved up the Hudson River, and across the Erie Canal, almost every summer, for years, often following specific arrivals of large numbers of people in ships from the Carribean, as well as Africa.  Like Zika, yellow fever needed to be present in mosquitoes at a certain level to threaten people, and outbreaks usually started in ports where more than ship at a time came in from Africa and the Carribean.   In some parts of the deep south, however, yellow fever became established, and simply broke out every year.   

Media and local health departments typically present a map where Aedes aegypti and Aedes albopictus have a certain probability of being found, and refuse to monitor these species, especially away from the coast, which annoyed and worried me into doing this project.   Experts who work with these mosquitoes are telling me that while coastal cities in the south are typically mobilized and monitoring Aedes mosquitoes, inland cities like Austin are pretty much ignoring the matter, even though we have the same mosquitoes.  I think that pretty much the only mosquitoes we don't have here, that south Florida does, lay eggs in pitcher plants that grow in the swamps of south Florida.

Here are photos with my new LG cell phone, which has a weaker camera but higher resolution.

The first photo is Aedes aegypti, the second and third are Aedes albopictus.

At the end of September, Alex Wild got ahold of a CDC style (CO2 baited) mosquito trap.  His yard always gets lots of Aedes aegypti and Aedes albopictus.   He put the trap out, with CO2 only for bait, and the Aedes aegypti came running.   He posted about this on Twitter, and researchers in the Dallas area who were looking for a source of Aedes aegypti for research came running.  (This seems highly remarkable, since Aedes aegypti and Aedes albopictus have consistently been found to take little intereste in CDC traps that are baited with light and CO2; it could conceivably be something about the recent rainy weather.)   They put the trap out for one day and caught several hundred Aedes aegypti mosquitoes, and later reported that they were able to infect half of them with Zika.   They are specifically studying bacteria that keep mosquitoes from contracting Zika or keep them from transmitting it, similar to Wolbachia.   

I borrowed the trap for two days.   The first evening and the following morning I hung it on my back porch near my traps where there are usually plenty of mosquitoes, and the second evening I hung it in the shade in front of my house.  (The back porch is shaded but not deeply.)   The front entryway has an old fashioned incandescent bulb that is on at all times.   

In addition to CO2, which is placed in the insulated upper container and CO2 gas comes out through a hole in the bottom, I put a nonanal lure on the roof of the trap.   One can see it as a small white object by the black light bulb.   Alex did not use a noanal lure.

 Nonanal has been known to make the difference in whether Aedes mosquitoes will come to a CDC type trap.  It is a chemical produced by people, birds, and flowers, that attracts mosquitoes, and it is an important reason why Culex mosquitoes that normally target birds often bite people as well.   

The fact that it is in flowers is important, because most mosquitoes drink flower nectar for energy, and drink blood only for substances they need to make eggs.   In fact, Alex Wild thinks that the reason for so many Aedes aegypti near his home in a semi-suburban environment may have to do with a nearby cemetery.   Research consistently finds that the favorite containers of Aedes aegypti and Aedes albopictus are tires and dark plastic flower vases in cemeteries.  One theory of the spread of Aedes albopictus in this country involves cemeteries and used tire lots placed near each other!   I have at times put flowers in my traps over the summer, and the strategy is modestly successful, though it must be said that numbers of mosquitoes visiting my traps went up and down.

Some people, including atleast one local health department that I talked to that actively monitors Aedes mosquitoes, bait mosquitoes for Aedes aegypti with hay.  One would expect that strategy to work on Culex, since it quickly fowls the water, and I found that it does, and also attracts large numbers of midge larvae.   Typically Culex want stinky water, such as in the sewage pond under the bridge near my house, and Aedes will only lay eggs near clean water with some organic material or bacteria in it.

On 9/21, 7 PM to 9:30 PM, I caught 2 Aedes aegypti and 6 small moths.

On 9/22, 8 AM to 1 PM, I caught 1 Aedes albopictus, one culex, and 1 small moth.

On 9/22, 5:30 PM to 9:30 PM, I caught 2 Aedes albopictus and 2 Aedes aegypti.   

The UV light went on only the first evening.  Alex thinks the battery may have been getting weak.   I noticed that more mosquitoes seemed to check out the trap and hang around it than get caught.   It is possible that the weakest fliers, which would be Aedes aegypti, were disproportionately caught by this trap.   




Culex adults

These larvae began appearing in my tire traps around the second week of June.   I grew them into adults before trying to identify them.  One of them was found on the rim of the bathtub, having evidently gotten burned on the lightbulb overhead, or electrocuted on the wires, which used to happen to ants regularly.

Below are quite a few of my Culex photos.  Alex Wild said they are generic Culex quinquefasciatus.   Tinkerbelle might not be; try to decide if his legs are vertically striped or vertically patchy.  Culex quinquefasciatus, which is the southern variant of Culex pipiens, has a number of close cousins that look so similar that very small details tell them apart.   Color and abdominal patch variation don't seem to be the most important features as they vary considerably within species.   The details that distinguish Culex quinuefasciatus from Culex pipiens, which is also common in central Texas, are small indeed.   Science recently decided they are two species, based on very little.   

My most detailed photos and a long section of information from various keys on distinguishing the Culex species, is here.

These are photos from online of Culex mosquitoes, mostly Culex quinquefasciatus.   The Culex mosquitoes look pretty similar, and Alex Wild at UT's entomology lab didn't want to key them because it is hard to key Culex mosquitoes.   While culex pipiens (in the northern part of North America) and culex quinquefasciatus (in the southern part of North America and much of the rest of the world) are found breeding in small containers like tires and cemetery flower vases, far more often than other Culex species, it isn't unusual for several other species to be found there.   All of these species carry the same diseases; West Nile virus, other forms of encephalistis, equine encephalitis, and dog heartworm.   From a health standpoint, it is not very important to pin down mosquito identification past the genus Culex.

This mosquito, which is perfectly identical to those below, appeared on a forum discussion on identifying a Culex nigripalpus.  It wears the file name Culex quinquefasciatus but appeared to be identified in the post as Culex nigripalpus.  

But the same photo is found in a discussion of Culex quinquefasciatus at New South Wales (Australia) Arbovirus Surveillance & Vector Monitoring Program

It's author, Richard C. Russell, an entomologist in Australia, says it is his photo, and it is Culex quinquefasciatus.   

Specifically, the pattern on the abdomen, the general coloring, the color of the head, "nose" and proboscis and palp is the same, and the color pattern on the legs is the same.   

I named him, Tinkerbelle.   This is the guy who fell on the bathtub.


My most detailed photos and a long section of information from various keys on distinguishing the Culex species, is here.


Differences in Mosquito Larvae Behavior

I have found that Culex and Aedes larvae act very different.  Culex larvae are largely passive.  If you actively disturb the container or the water they head for the bottom of the container, where they simply sit there, and they soon come doing their head over tail thing back to the surface.  I've never seen a Culex larva try to hide.   If you put them on a slide they thrash around, but not as vigorously as an Aedes does.   If you take out all but half a drop of water, they simply lie there and breathe unhappily.  Aedes aegypti are extremely feisty, nervous, and intelligent.  If you look at them too hard, they dive to the bottom of the container and try to hide in any algae or vegetation, and don't soon return to the surface.  They know when someone is looking at them; forget about touching their container.  On a slide they thrash continually and rapidly.  If you remove all of the water, they crawl out of the slide pit and off the slide, and start crawling across the counter.  Since they evidently don't need water to breathe, it isn't hard to imagine that they need only a very small quantity of it to grow into full fledged mosquitoes.   One supposes that if their water drop dries up, they just go in search of another one!   If you refrigerate them, they are vigorously thrashing around again two seconds after you put them back under the microscope.   What is more, Aedes aegypti larvae actually don't spend a whole lot of time suspended from the surface of the water the way Culex does.  They are found there sometimes, but spend a lot of time on the bottom, hiding, and eating, and even hanging out in a group among the algae.  It seems  possible that they can breathe air but don't have to.  

I think that I have figured out what is up with Aedes aegypti's apparent awareness of whether people are looking at them with the nervous tendency to rabbit.  I work in a warehouse environment where people have no grasp of the entire concept of keeping the big garage-type doors closed when people are not going through them or unloading goods, not to mention that we get items in from all around the country and possibly farther away.   The other night, around 9 AM, inside the brightly lit warehouse, I saw a small mosquito hanging around me.   At one point I lost visual contact with the mosquito.  Since the warehouse is only a block and a half from my house, and it looked like an aedes aegypti, I knew it was probably an Aedes aegypti.   I looked around for it.   Mosquito was on the back of my elbow.  When I swatted at it it flew off.   It is well recognized that Aedes are very sneaky, and that they prefer to bite people on the elbow and the ankles where one doesn't see them.   Since Aedes hangs out close to the ground that explains ankles, but one has to really wonder how an Aedes aegypti knows what part if a human anatomy is its elbow?   It makes good sense to suspect that what the Aedes aegypti knows is what part of the human she can bite when the human is not looking at her.  So she knows when she approaches human skin out of eyesight of the human.  


Ease of Finding Aedes aegypti and albopictus in Austin; where are they found?

At first, I found entirely Aedes aegypti and no albopictus.   However, for the past several weeks, there have been increasing numbers of albopictus, until most recently there are half aegypti and half albopictus.   Most of my mosquito larvae are coming from my bicycle tire, with only two or three at a time from the larger tires, while the larger containers have large numbers of mosquito eggs above the water line on the paper towel covered popsickle sticks, in the bigger tires.      Alex Wild says he is finding a lot of Aedes aegypti, and is also finding Aedes albopictus.  He is especially finding both species as adults in his own back yard and garage.  He lives in south central Austin, and says that for instance, one day last fall his garage was full of Aedes aegypti flying about, but that isn't the only place where he has found them.  (We agree that a single Aedes aegypti probably laid eggs in his garage.)  He is especially finding them in the flower vases people leave in cemeteries.  He traps more adults than eggs and larvae, and says he has no idea where the Aedes albopictus are breeding.  

The literature leads one to believe that one or the other species should predominate, and either albopictus will always drive out aegyti, or which species dominates depends on environmental conditions, and, in the lab, on such differences as their food source.   

Until the 1980s only Aedes aegypti was found in this country.   When Aedes albopictus moved into areas dominated by Aedes aegypti it soon out competed them.  Noone knows why.  It would be interesting to see if the tide may be turning back.   Because only Aedes aegypti was found in the U.S. until the 1980s, and UT's bug collection is older than that, the UT bug museum contains Aedes aegypti specimens mounted to cards, but not albopictus.   Finding out would take entomologists and public health authorities, or anyone, bothering to actually monitor the two species, instead of publishing maps of the relative likelihood that they are present in any particular southern city.   In Austin, public health authorities exclusively monitor Culex pipiens, and send what they catch off to be tested for west nile virus, as if there are no other diseases on earth.  

In the United States, it was initially found at the Port of Houston in a 1985 shipment of used tires, then spread across the South and up the East Coast to become prevalent in the Northeast.[41] It wasn't discovered in Southern California until 2001, then eradicated for over a decade; however, by 2013 it was again being found in Los Angeles County traps, then over the next two years expanded its range to Kern County and San Diego County[42] [43] [44]North American land that suits the environmental conditions of the Asian Tiger mosquito is expected to more than triple in size in the next twenty years, especially in urban areas where the majority of residents reside. This will introduce new health prevention issues as more people become exposed to infection by this species. [45]

]Aedes albopictus can outcompete and even eradicate other species with similar breeding habitats from the very start of its dispersal to other regions and biotopes.[55] In Kolkata, for example, it was observed in the 1960s that egg depositing containers were being settled by the Asian tiger mosquito in city districts where the malaria mosquito (genusAnopheles) and yellow fever mosquito (Aedes aegypti) had both been eliminated by the application of DDT.[56] The reason why, in this case, may be due to the fact that primarily the inner walls of the houses were treated with DDT to kill the mosquitoes resting there and fight the malaria mosquito. The yellow fever mosquito also lingers particularly in the inside of buildings and would have been also affected. The Asian tiger mosquito rests in the vicinity of human dwellings would therefore have an advantage over the other two species. In other cases, where the yellow fever mosquito was repressed by the Asian tiger mosquito, for instance in Florida, this explanation does not fit.[57][58] Other hypotheses include competition in the larval breeding waters, differences in metabolism and reproductive biology, or a major susceptibility to sporozoans (Apicomplexa).[59

What often happens with Wikipedia, is that different people who added to the article, put different ideas into paragraphs where they seem to logically belong.  The result can be sentences that contradict each other.  Details don't necessarily have to be added if the ideas are suitably referenced.  Each odea is well referenced, but you have to read carefully to put together a picture that makes sense.   The paragraph begins by stating broadly that Aedes albopictus can outcompete and even eradicate other species with similar breeding habits from its introduction to different places.  No specifics are given, just a reference to the article that tells us this, and could represent a set of statistical observations with no effort to explain them.   Next come specific examples.  In Calcutta, the Asian tiger mosquito moved into an environment where intervention had removed Aedes aegypti and certain other competitors.  The intervention specifically targeted Aedes aegypti in internal walls of houses, and while Aedes aegypti is mainly found inside houses, Aedes albopictus is also found outside and near houses, which gives the latter an advantage in this situation.   But in Florida where Aedes aegypti was suppressed by Aedes albopictus, that explanation doesn't fit.   This gives references but not a single detail.   Other hypotheses explain possible relative advantages between the two species

This article leaves open the possibility that specific situations caused Aedes albopictus to take over places that had formerly been the territory of Aedes aegypti.   There isn't actually any specific information given as to why one species may have done better than another over time.  So Wikipedia actually sheds only a possible beginning of light on the subject, but it does offer the sources to pursue for more information.  

The articles cited in the Wikipedia article, or atleast their abstracts, strongly and consistently show that Aedes aegypti has an adaptive advantage in inner cities, and Aedes albopictus has an adaptive advantage in suburban and rural habitats, and that this is partly because Aedes albopictus thrives where people aren't necessarily less than 500 feet away, and utilizes natural as well as man made containers for laying eggs.

Carrieri et al (2003) found that Culex pipiens and Aedes albopictus both breed in medium sized containers.  When they do, Ae. albopictus is more efficient than Culex pipiens at transforming food into biomass.  Where food is scarce, competition takes place and is influenced by temperature.  Ae. albopictus is more likely to prevail at 25 degrees C than at 20 degrees C.  To watch Culex and Aedes grow, one can see several reasons why that might be the case.   I have found Aedes aegypti growth to be more influenced by temperature than Culex pipiens growth.   The Aedes larvae are also far more active and more nervous than the Culex larvae, so they would be expected to eat more.  This may be reflected in the greater tendency of the Aedes larvae to be hanging out where food is, usually on the bottom of the container.   

O'Meara et al (1995) simply provide important pieces of more information on what is taking place.   I have access to the abstract.  Broadly, Aedes albopictus has spread in northern Florida, and declines in the abundance of Ae. aegypti are associated withteh explansion of Ae. albopictus in both urban and rural areas.   But that is not the entire story.  In central Florida the same thing is broadly true, but in some urban areas Ae. aegypti has remained the common mosquito long after the arrival of Aedes albopictus.  In southeastern Florida, Ae. aegypti is currently the dominant container-inhabiting Aedes in urban areas, while sites dominated by Ae. albopictus are in rural settings or in undeveloped tracts of land within urban or suburan areas.   It looks as though Ae. aegypti may be able to do better in urban habitats, atleast in the southern part of Florida.   To me, it makes sense that Aedes albopictus would prevail in areas a little bit away from houses, since this species is far less tightly restricted to living within several hundred feet of human blood meals.   In a 1997 article, the same authors found that while rock-hole inhabiting aedes species are far more likely than albopictus to be found in rock holes, Aedes albopictus is found there.  Moreover, Ae. albopictus is frequently found in samples from tree holes as well as artificial containers.   

O'Meara et al (1992) found that in the same cemeteries in 11 Florida counties, both albopictus and aegypti were found in 70% of containers that contained Aedes species at the start of the season, but in subsequent collections there was a progressive decrease of Aedes aegypti in the containers.   It was also observed that the larvae had trouble surviving in bronze containers, and that Aedes albopictus often became well established in cemeteries before appearing in nearby accumulations of waste tires.   These authors suspect that plastic floral baskets are helping the spread of albopictus.   I only had access to the abstracts.  (In another article, the same authors found that immature mosquitoes were found in 60% of stone cemetery vases lacking liners or with aluminum liners, but far fewer vases with copper liners.)  G.F. O'Meara seems to have published between 1970 and 2006.  In 2004 he was professor emeritus at the Florida Entomological Laboratory.  

Barrera (1996) conducted an experiment to examine resistance to starvation in Aedes aegypti, albopictus, and triseriatus fed decomposing leaf litter.  The Ae. albopictus developed faster and had greater survival.  These authors noted that in other studies, when fed non-natural food in a laboratory setting, it is Aedes aegypti that do better.  It evidently makes a difference what the larvae are eating.   While this and similar research cited by Juliano (2005), support a competitive advantage of one species over the other when the larvae grow together, it does not seem to be as important in explaining what species becomes dominant as the nature of the environment.   In another study, Juliano et al (2004) added Aedes albopictus under varying conditions to cemetery vases, and found once again that there was interspecies competition, but it did not overall affect the numbers of Aedes aegypti.  The two mosquitoes certainly get along in the same cemeteries with no problem.

Moore et al (1988) point out that Aedes albopictus is far less dependant on a single meal source and a single environment than is Aedes aegypti.  Aedes albopictus in its native habitat in Asia primarily lives at the forest edge, giving way to other Aedes species inside forested areas.   It has readily adapted to container habitats introduced by humans.   It could colonize tree holes and other similar habitats in the eastern U.S..   They also state that the U.S. straints of albopictus are of northern Asian origin, and may do better than aegypti in the more temperate ecological zones of the U.S.   

Gilotra et al (1967) also found that Ae. aegypti does better in the urban setting while Ae. albopictus does better in suburban and rural settings.  They collected larvae from all sorts of breeding places in a wide variety of places, in Calcutta, India, in the 1960s.  Ae. Aegypti was predominant in houses and tenements in urban areas, while A. albopictus was found there.   Both occurred in equal densities in small urban gardens.  In suburban and rural areas, A. albopictus was predominant or else the only one of the two species present.  It readily entered houses to lay eggs, especially if Ae. aegypti was absent.  The authors think that the two species outcompete each other in different environments.  It is possible that if Ae. aegypti were eradicated in the city, the population of Ae. albopictus there might increase.  

Hornby et al (1994) collected Aedes eggs, near Jacksonville, in northeastern Floria, at what at the time was the southern limit for Ae. albopictus in Florida.  They hatched the eggs in the lab and grew the larva into adults, and counted the relative frequency of each species by gender.   They set up egg traps in a variety of sites, near or on the ground, near tires, assorted containers, and oak trees.  They collected eggs for an entire year.     335 Aedes triseriatus eggs were collected, out of 25,000 eggs.   Despite the legendary ability of their eggs to withstand drought, Aedes aegypti is selectively very active in laying eggs during rainy periods.   Aedes albopictus were found in the northern part of the range.   They were found most often in undeveloped or sparsely developed places.  Aedes albopictus frequency strongly tended to favor suburban and rural locations.  

Kaplan et al (2010), after reviewing most of the above, put forward a convoluted demographic model that basically states that if two species directly compete in different environments, in each kind of environment, the species that has the advantage in that environment will tend to reduce the others' numbers to zero.  They illustrate this with data from Bermuda, where aegypti and albopictus appeared to drive each other to exctinction in different places in a quite convoluted manner.

Bargielowski et al (2012) review an argument that strange things happen when Aedes albopictus and Aedes aegypti can potentially mate with each other.   The two species are evidently as closely related as they look and act.   They are on the edge of biological incompatibility.   Genetic research has established, for instance, that modern humans and Neanderthals could successfully mate in one direction but not the other, due to an incompatibility on the Y chromosome of one subspecies.  Surviving Neanderthal DNA in modern humans outside of Africa makes it clear they did successfully mate, but not very often.  Their DNA may also have not always combined very well.  It seems that mostly a select small amount of Neanderthal DNA of obvious potential genetic advantage has come down to us.  

I found a mention of studies by Toumanoff in 1937, discussion of which was truncated in the Google books version.  Toumanoff crossed female A. albopictus from Hanoi and male A. aegypti from Calcutta, and the offspring produced fertile offspring that resembled their mother.  Offspring remained fertile to the 4th generation.  Crossing female aegypti and male albopictus occurred but "was not successful"; it produced either no viable young or no fertile young.   It seems that this would tend to favor a preponderance of mosquitoes that are or key as albopictus, even though at the 4th generation many are still genetically hybrids.   

Aedes aegypti and Aedes albopictus belong to the subgenus Stegomyia, and have similar life histories and mating behavior.  

Bargielowski makes contradictory statements about the prospect of the two species producing viable and fertile offspring, but offers a very different idea of how cross species mating affects the fate of each species.  They thinks that when they first meet, the two species may often mate by accident and produce no viable young at all.   Therefore the outcome would depend partly on any bias in who mates with who.   There are recent findings that A. aegypti and A. albopictus mate bidirectionally where both occur in Florida, and hetrospecific male accessory gland products make A. aegypti but not A. albopictus females refractory to further insemination by males of their own species; in other words, sterile.  They first established that interspecies crosses were 98 to 100% inseminated.  Almost four times as many A. aegypti females were inseminated by A. albopictus males than the reverse.  This would tend to suppress A. aegypti populations.  However, these authors think that, since this is very maladaptive, over time the two species learn to avoid each other, and the numbers of Aedes aegypti recover, leading to patchwork relative distributions of the two species.   

This idea does not account for the consistent pattern to the patchwork, in favor of determination of competitive success by type of environment.   The experiment described also did not prove that the matings would not have produced viable or fertile young.  I also did not see where either this study or the other study that was cited, proved the notion that cross species mating renders some of the females infertile.   

A map by the California Department of Public Health of the distributions of Aedes aegypti and Aedes albopictus, frankly seems to me to offer the strongest evidence for thinking that there is inadequate monitoring of Aedes mosquitoes, or maybe any mosquitoes, in the more rural parts of California.  Aedes aegypti is found all over central and southern California, in the western and central counties.  It is found as far northward as San Francisco.   Aedes albopictus is found only on the southern coast of California, and Aedes aegypti is found in every county where Aedes albopictus is found.   Most places are not listed for both types of mosquito, but a few are.   Those are San Diego, Santa Ana, Los Angeles, Pico Rivera.  This doesn't make sense.  To begin with, the range of Aedes albopictus in California should be larger than that of Aedes aegypti, and particularly should range farther north.  The map seems to show Aedes aegypti well distributed in every county that ever looks for a mosquito, and Aedes albopictus selectively found only in the more urban parts of coastal southern California.   

As far as looking for mosquitoes, experts I spoke with today told me that the coastal cities of Texas are very well organized and doing excellent surveillance for Aedes species, while the inland counties such as Travis County are taking more of a so-so attitude.  Such a pattern is consistent with the reported incidence of Aedes species in California.  Federal officials at the USDA and CDC do not think it is possible to draw many conclusions from such a pattern of surveillance.  

Generally it appears that rather than Aedes alobopictus taking over the territory of Aedes aegypti, they are each favored by specific environments.  Tending to find Aedes aegypti more often than albopictus in central Austin is consistent with this.

It also appears that evidence of Aedes aegypti is far more likely to be found during the relatively rainy parts of the year.    This suggests that what mosquitoes one finds can depend on when one does surveillance.  In Austin this means that during the hottest parts of the summer, as well as during the winter, fewer of them should be seen. 

Simard et al (2005) studied what kinds of containers both Ae. albopictus and Ae. aegypti are found in, in a range of places in Cameroon.  They searched for larvae and pupae in a variety of natural and man made containers.   They expected to find Ae. aegypti predominant in cities, and Ae. albopictus predominant in suburbs and rural areas, partly because Ae. albopictus is known to breed in natural as well as manmade containers.   Aedes albopictus has only been seen in Cameroon since 2001, but evidently spread rapidly, being found throughout the southern and central parts of the country.   In places where both species were found, their larvae were often found in the same containers.   Both species had a strong preference for used tires.   


What containers are Ae. albopictus and Ae. aegypti found in.

Simard et al (2005)  Containers varied from 5 ml to 100 liters of water.   The most common natural breeding sites were tree holes, rock holes, dead leaves on the ground, and cacao shells.   Albopictus were also found in leaf axilla, snalil shells, and cocunut shells.   In southern Cameroon, both species were most often found in used tires, discarded tin cans, pastic containers of any sort, earthenware jars, abandoned car parts, and brick holes.    In northern Cameroon, Aedes aegypti favored used tires, earthenware jars, gourds, and water storage pots.   They found Aedes aegypti atleast as likely to be found in tree holes and rock holes, and dead leaves on the ground, as Aedes albopictus.   




Will Aedes aegypti grow in a bottle cap?

On the Entomology Discussion List run from Guelph University, people have been discussing whether Aedes aegypti can really grow to maturity in a bottle cap.    One individual tried it, and found that the water in the bottle cap evaporated far faster than even aegypti in hot weather can mature - within a day.   He said he had the bottle cap outside in the shade.   

Reasonably, even though allegedly Aedes aegypti can grow to adulthood in a drop of water, and they've proven to me that all they need to be is kept wet and able to eat, they aren't going to grow if their environment dries out.   Allegedly it is also true that if Aedes stops growing it starts again when conditions are more favorable, but I think that was talking about temperature.  

I decided to do my own experiment.  I had to make sure nothing eats or knocks over my larvae, and that if they do mature they don't fly away, so already they are in a covered container, though one with holes for ventilation.  I suspect it may be necessary to add water.

I think that what was actually found in bottle caps was larvae, meaning it hasn't necessarily been proven that they would have become adults.  

I started this experiment at about 10 AM, on Tuesday, June 7.

June 8 - bottle caps were half full and refilled them.    The bottle caps I found around the complex and added only food and water to were damp with most water in bottom of container so I refilled them.

June 9 - larvae have hatched from the eggs in my bottle caps.  Nothing in the bottle caps I picked up.   It typically takes two days for mosquito eggs to hatch, and evidently Aedes aegypti isn't better at it.

June 10 - bottle caps half full and young half grown larvae vigororously swimming around.

June 14, PM - adult mosquitoes emerged; four from the larger bottle cap and five from the smaller one; all of the original eggs produced mosquitoes.   So it took them six days, at ambient daytime temperature in mid 80s when I started and mid 90s at the end.  (That is time for more or less twice weekly trash pickup to keep them from multiplying in the trash dumpsters.)   

Since the eggs were originally laid on damp paper towel above the water line in my ovitraps, and then dried, I know they came from Aedes aegypti or Aedes albopictus, but there is no way to tell the difference by looking at the eggs.   When I froze the grown mosquitoes and looked at them under low power, they were all Aedes aegypti, mixture of male and female.

I also looked into where the often quoted information that Aedes aegypti can mature in a bottle cap came from.

Barlett-Healy et al (2011) couldn't determine where it came from, but, instead of trying to grow mosquitoes in bottle caps to see if it works, they experimented with water in bottle caps, and developed statistical models of the chances that common container mosquitoes could reach maturity in a bottle cap.  They determined that at some temperature and shade conditions, in some types of containers, both Aedes aegypti and Aedes albopictus could develop within a bottle cap before complete evaporation.  They used maturity rates from other literature, of how long it takes Aedes albopictus, aedes aegypti, and Culex pipiens, to mature. For Aedes that is 10 das at 24 degrees C, and 6 days at 34 degrees C.  

They also cited literature that may explain why Aedes albopictus is selectively showing up in my bicycle tire.  They favor smaller containers.

It appears that one major source of this idea is things mosquito experts have said in the media and in books they have written.   For instance, Joseph M. Conlon, an entomologist and technical advisor to the Mosquito Control Association, was quoting in an online article, as saying, "I've seen Aedes aegypti breeding in discarded soda bottle caps.  They're survivors."   

Unlu et al (2013) cite other studies that discuss where Aedes albopictus and aegypti larvae are found, and mention finding larvae even in bottle caps.    This supports thinking that no studies have been done of whether these mosquitoes reach maturity when they hatch in bottle caps, just that they hatch there.   It must be said that the studies I have seen of where mosquitoes breed actually studied where eggs or larvae were found.   Since evidently Aedes can hatch very quickly when their environment is flooded, they must surely hatch in many places where they never reach maturity.   The entire principal of simply dumping water in which mosquitoes breed on a regular basis assumes that mosquito larvae that are thus dumped don't reach maturity.   

They are reaching the pupa stage in my used tire egg traps, and Aedes aegypti only breeds in them, and hasn't gone extinct yet.

It looks to me like one reason why mosquitoes breeding in bottle caps is mentioned in the media, is to get urban residents who aren't all that bright or well educated and wouldn't normally take the situation seriously enough, to understand that they must control ALL of the trash!   

I also observe that the people on the Entomology list seemed to think the entire matter was a joke.  They didn't take it seriously, but raised it to relieve early summer boredom.

I suspect, though, that a related idea that needs investigation is the notion that Aedes needs only a drop of water to reproduce, together with the notion that they can reach adulthood in three or four days, which I have yet to actually see happen.   Investigation of Google hits suggests that this also is based on where Aedes aegypti eggs have been found.   However, it seems that experts are being quoted in the media as saying this.  "Ballenger also points out that mosquitoes only need about three drops of water to grow... 'Insecticide fogging is still an important part of mosquito control because it's hard to find the habitats,' he says, asking me to consider how hard it would be to eliminate spots that hold even a quarter cup of water. "   Joe Ballenger is an entomologist, molecular biologist and science communicator who writes at Ask an Entomologist and helps run the Entomology public Facebook group."   (Pestweb, reprinted from Forbes)  Forbes won't let me read their site without removing my ad blocker, and I"m not stupid enough to do that.  

I must emphasize that whether or not Aedes mosquitoes can effectively breed in bottle caps, inner cities need proper trash control, and the poor need to clean up their litter.

However, it occurred to me to wonder why Aedes aegypti would lay eggs in bottle caps.  My guess is they don't.   I think that sometimes Aedes DO reach maturity in bottle caps, but the reason why is that the ecology of Aedes mosquitoes and bottle caps is complex.  

Since bottle caps aren't likely to attract Aedes to lay eggs, if larvae have been found in bottle caps, they or the eggs got there from somewhere else nearby - though they could also have been laid in bottle caps that contained a small amount of water.   It is also possible that something in or near the bottle caps caused the mosquitoes to lay eggs there.

Typically Aedes aegypti lays eggs just above the surface of water, and also on damp soil, where she thinks it will rain or flood, and the eggs can hatch, even if they dry up in the meantime.   Water she lays eggs near must be clean but have organic matter in it, so that her young will have protozoa to eat.   

Aedes aegypti normally only occurs in a certain environment, and that isn't a pristine laboratory with filtered air and air conditioning .  Aedes aegypti is largely a creature of human ghettoes.   It thrives where large numbers of people are outside, they don't have air conditioning, they don't even have fans, and there aren't screens in the windows.  Large amounts of trash always lies around outside.  If tires are there too, that's REALLY a favorable environment.   

Bottle caps are also plentiful in the trash-littered inner city environment.  They occur under a complete variety of circumstances.   They vary completely in opportunities to gain mosquito eggs, and opportunities to stay wet.  



In an environment like that, what are the odds that the larvae in the bottle cap didn't hatch from eggs laid nearby, that something nearby didn't cause the mosquito to lay eggs in or near a bottle cap, and even that something else in the environment won't tend to maintain water in the bottle cap?

I took a tour of the inner city housing complex where I lived, paying special attention to where there are or might be bottle caps.

The superintendent asked me what I was doing, and when I told her I'm looking for bottle caps, because I want to know if Aedes aegypti can really grow in bottle caps, she told me, "there will always be mosquitoes wherever there are trees."   I looked up from the bottle cap I was looking at, and, behold, a great big tree!   She is right.  Aedes albopictus will breed in tree holes, and the trees that line our parking lot are full of tree holes.   You will see what I actually found in a particularly large tree hole that is crowded with flying insects after it rains.  

I took a tour of my inner city housing complex.  I photographed bottle caps where I actually found them.   

The right hand bin is open.  One of the big trash bins is always open; people wouldn't be able to open and close it if they wanted to.  The tire had rainwater in it, and I wasn't able to drain the rain water out.

The orange bottle cap above is sitting in rain water on the bottom of the open garbage bin.

Look up....  (Bottle cap is on the ground in the foreground under the tree.)

When we really get a lot of rain, these front yards are actually under water.   Eggs that hatch didn't necessarily originate where they hatched.  But a bottle cap with organic matter in it might let them live long enough to reach maturity.

Hmm, what are the random odds that Aedes eggs might be found in a bottle cap among the leaves under a rainspout!

The bottle was already in the shoulder high tree hole.  People are throwing trash up there.

Get the idea?

In my neighborhood people often sit outside on the steps that lead to the second floor, or stand around in groups, wearing shorts and no shirt or a tank or halter top, never mind whether their screens have windows!   I got bitten twice, once on the elbow, just walking around the parking lot at 11 AM.   

I put some of these dirty bottle caps found in dirt and among leaves, in a container with some bits of leaf and water in them, and I'll wait and see if something hatches.  My previous efforts to find where Aedes albopictus normally breeds around here suggest that something is likely to hatch, though it may not be mosquitoes.   


Politics of Government Attention to Zika, Dengue and Yellow Fever

This is why so few local governments in Texas are actively concerned about the matter.   Dengue outbreaks here usually occur in very impoverished inner city neighborhoods, and border settlements where the residents are Hispanic and very poor, or even illegal immigrants.   Texas has to be lived in to be believed; even inside the city, many streets don't have street lights.   Outside the cities, there are few libraries, few health clinics, and few street lights.  Even paving the roads is very often problematic.   My sister lives inside an entire network of roads the neighbors paved themselves.   The place pretty much resembles England in medieval times.  It's that Texans have a medieval belief system when it comes to spending money and resources for the common good.   If something disproportionately afflicts the poor, you might see a crocodile tear, "the poor things", or you might get a more straightforward "they need to die," or, "they were born to die",  but you'll seldom see people hired and facilities equipped to deal with the problem!   Neurologically children would just join the ranks of the mentally disabled, who already find it difficult or impossible to get care in Texas.   

The book, "Yellow Fever and the South", by Margaret Humphreys, makes it clear that very little has changed, across the deep south, from conditions that sprang into major epidemics and forced communities to deal with how the poor in their communities lived.  Otherwise the denial, and the political corruption, that surrounded issues that pertained to public health was ridiculous, and it's still ridiculous.    I hear it in the voices of my local health department vector control people telling me that only West Nile virus is a threat!   West Nile virus is carried by a mosquito that mostly lives in trees, breeds in any stagnant water as well as in containers, mostly bites birds, and attacks people of all social classes.  It also doesn't usually make people sick, rarely makes people very sick, and even more rarely has permanent after-effects.   People are worried about it because the media plays up stories about severe illness in middle class people.  Zika and dengue also mostly affect the poor in South and Central America.  The differences are that their less radically Capitalistic governments make health care available to the people for free or little cost, and they actually care about the welfare of their people, and they will spend the money it takes to treat neurologically damaged children; and, the United States sees a chance to intervene on behalf of the afflicted poor in the underdeveloped world.   

One reason why the public is very concerned about the issue at the moment, is that it is affecting middle class people who travel to South America on business and for recreation.  Large numbers of people in the country are affected, and severely neurologically damaged children are beginning to be born, to the middle class.  Public officials can see that in modern times mosquito-borne disease isn't a threat to the upper classes, but the upper classes themselves don't really see that.   

However, many local governments appear to realize that Zika will most likely do what Dengue has done before it; break out sporadically in very poor neighborhoods in coastal cities and border communities, and prove easy to stop, at least for the time being.   That doesn't actually mean that noone else ever catches Dengue; I had a supervisor out with three weeks with Dengue, though I don't know if she caught it in Austin, Texas, where she lived and worked, or elsewhere.  But it seems to be uncommon and certainly has a low profile except for very occasional isolated outbreaks in very poor communities that just don't matter.   

It is the physical and mental disability to babies born to mothers who had Zika that is attracting the most attention, but I think that most middle class people don't think it will really happen to them.   In the Miami community where people have come down with Zika, media photos constantly show scantily clad women with babies and toddlers in carriages hanging out in public.   An attempt at a serosurvey found that 1/4 people who were tested had had Zika, but the overwhelming majority of people refused to be tested.   As to the public expense of disabled children, the state of Texas has the perfect answer; it doesn't provide for them, and doctors and hospitals won't treat them if they are on medicaid!   In the Dallas area it is hard for women on Medicaid to even find a hospital to give birth in or doctors to care for them.   Special education and other services for the disabled are scarce for all disabled children, and any who were affected by Zika would presumably join that club.   

As the summer wore on and Congress did not pass a $1.9 billion Zika funding bill, the CDC's tactics turned insteresting indeed.   It changed its official position from the truthful view that aerial spraying does very little for Zika-bearing mosquitoes, to urging localities to aerially spray, just to attract attention and look effective!   Most work to develop vaccines, research how the virus behaves, find ways to stop the mosquitoes from transmitting the virus, had in fact somehow already been done without the money.  Neuroscientists actually took up a high school student's cheap and effective solution to how to research how the virus affects the growing brain without large amounts of money.   Local health departments were either tracking Aedes mosquitoes or not according to their previously demonstrated wont.   This means that south Florida and Houston, Texas departments were doing an excellent job, as were sporadic health departments across the midwest, and the Travis County Health Department was of course doing its own exclusive sporadic monitoring of culex mosquitoes that somehow never finds west nile virus when adjacent Williamson County does, and usually it is found in adjacent Round Rock.  

Mosquito  identification resources

University of Texas at El Paso Mosquito Identification web site.   Easy to follow slide show key to identifying mosquito genera, larvae and adults.   

Wikipedia article on mosquitoes, with general discussion of mosquito biology and anatomy charts of larvae and adults.   

Waterwereld: The common house mosquito   Biology of mosquitoes, usefulness for fish food, usefulness of fish for mosquito control, diagram of mosquito larva anatomy.   It is controversial whether the common and southern house mosquitoes are subspecies of Culex pipiens.   However they share the ability to carry West Nile virus and other forms of encephalitis.

Mosquitoes:  Characteristics of Anophelines and Culicines.  Kent S Littig and Chester J Stojanovich.  Focuses on Anopeles, Aedes, and Culex (the three primary genera of medical importance in the U.S.)

Mosquitoes:  Characteristics of Anophelines and Culicines.  Kent S Littig and Chester J Stojanovich.  Focuses on Anopeles, Aedes, and Culex (the three primary genera of medical importance in the U.S.)  Same document from texasmosquito.org   

Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission   Exclusive key to Aedes species, but includes actual pictures of what scales, combs and hooks look like.  

Workbook on the Identification of Mosquito Larvae.   Pratt, harry D and others.   Public Health Service, Atlanta, Georgia.   Basic and detailed enough for a student to easily follow.  

Classification and Identification of Mosquitoes of New Mexico

A Handbook of the Mosquitoes of the Southeastern United States.   King, Bradley, Smith & McDuffie.  Agriculture Handbook No. 173, Agriculture Research Service, United States Department of Agriculture.  Very detailed text on mosquito collection and identification.  

Mosquitoes of the southeastern United States.  Burkett-Cadena, Nathan D.  (Tuscaloosa: University of Alabama Press, 2013) UT Life Science Library, QL 536 B916 2013.   Parts can be previewed at Amazon.   Someone on the Texas entomology listserve recommended this book.

Key characters for larval Aedes spp.  identification in California.   California Department of Public Health.   Photos of what anatomical features, such as hooks, look like.     

Identification Guide to the Mosquitoes of Connecticut  Detailed key with detailed illustrations.  

Identification Guide to Adult Female Mosquitoes of Saginaw County - photos of what the features look like.

Mosquito Identification Guide: Larval Quick Key  University of Florida, Florida Medical Entomology Laboratory.  

Mosquito Identification Guide: Adult Quick Key  University of Florida, Florida Medical Entomology Laboratory.

Photographic Guide to Common Mosquitoes of Florida   University of Florida, Florida Entomology Laboratory

SOUTHCOM Mosquito Genera Identification Key  U.S. Army Public Health Center.  For central and South America, but evidently there isn't one for North America.

Aedes larvae  Clear color photographs with distinguishing features of Aedes larvae

Aedes Albopictus Florida Medical Entomology Laboratory, University of Florida  Clear photos showing anatomomical features like scales and hooks

Aedes Aegypti  Florida Medical Entomology Laboratory, University of Florida  Clear photos showing anatomomical features like scales and hooks

Aedes Larval Picture Key  California Department of Health web site.  Photos instead of drawings, for three Aedes species.  

A rapid identification guide for larvae of the most common North American container-inhabiting Aedes species of medical importance.   Ary Farajolahi and Dana C Price.  Journal of the American Mosquito Control Association, 29(3):  203-221, 2013.  

Culex quinquefasciatus (Southern/ Common house mosquito, very similar to Culex pipiens and arguably a subspecies) Florida Medical Entomology Laboratory, University of Florida  Clear photos showing anatomomical features like scales and hooks, of larvae

The other main genera of mosquitoes are represented on this web site as well.

Culex quinquefasciatus  APHC Entomological Sciences Mosqiuto Species Page, shows in clear photographs, all of the fine anatomical detail necessary to identify this species.

Mosquito species pages/ training aids, Army Public Health Center (under training aids)

Species pages and keys with terms, Army Public Health Center

Walter Reed Biosystemacits Unit interactive key

Culex quinquefasciatus  Wikipedia   Describes relationship between Culex quinquefasciatus, the southern house mosquito, and Culex pipiens.   

Crowdwourcing for large-scale mosquito (Diptera: Culicidae) sampling.   Elin C. Maki, Lee W. Cohnstaedt.  Report on an earlier generation of the North American Mosquito Project, by the USDA.  Citizen science project that addresses the failure of local agencies to track mosquitoes.  Lists the agencies that helped them with their work.  The word Texas is notably missing from the list.  

Citizen-scientists:  Uncle Sam wants you to fight Zika!  The Invasive Mosquito Project.   New incarnation of the North American Mosquito Project.  The USDA and CDC are attempting to use citizen egg, larva and adult mosquito efforts to compensate for the poor job local agencies around the country are doing monitoring mosquitoes, especially disease-bearing invasive species like Aedes aegypti and albopictus.  

Walter Reed Biosystematics Unit  U.S. military public resource on medically important arthropods, includes several kinds of pictorial and interactive identification keys


My Evernote Notebooks

I have a collection of articles on Zika and its mosquitoes in Evernote notebooks.

My web page on the mosquitoes in my back yard


Zika Evernote links

https://www.evernote.com/pub/villandra/biologyofzika    Articles on evolution of zika virus, evolution of Zika virus, structure of Zika virs, mode by which Zika infects causes infection, how and which mosquitoes carry diseases, treatment of Zika, origins of current epidemic.

https://www.evernote.com/pub/villandra/bloodsupply  specific articles on Zika and the blood supply

https://www.evernote.com/pub/villandra/chikungungya  Articles specifically on Chikungunya

https://www.evernote.com/pub/villandra/conspiracytheoriesofzika   Conspiracy and nonsense popular theories about Zika

https://www.evernote.com/pub/villandra/ecologyofzika   Conditions in which Zika bearing mosquitoes thrive, in general and in specific environments.  Settings where it grows around the home.   Unique biting habits of zika bearing mosquitoes

https://www.evernote.com/pub/villandra/malaria  Historical articles about malaria in the U.S.  

https://www.evernote.com/pub/villandra/mosquitocontrol   controlling zika populations, research on ways to decrease Aedes aegypti populations, egg traps, 

https://www.evernote.com/pub/villandra/mosquitoidentifiation  material on how to identify mosqiutoes.  There are also links to such material on my web page.

https://www.evernote.com/pub/villandra/mosquitorepellents  Which mosquito repellents work for Zika bearing mosquitoes

https://www.evernote.com/pub/villandra/neurologicaldamage  Research on zika and neurological damages, to fetuses and to adult humans, and research on how Zika damages the fetal and attacks adult nervous system

https://www.evernote.com/pub/villandra/olympics  Discussion about Zika at the Olympics

https://www.evernote.com/pub/villandra/otherbugbornedisease   Other diseases that are carried by bugs.  Sand flies and kissing bugs carry parasitic diseases that are of growing concern in Texas.

https://www.evernote.com/pub/villandra/symptoms  Articles that describe the symptoms of Zika, which are often dramatic, often resemble dengue, often cause the disease to be misdiagnosed as dengue or malaria, and basically are often nonstandard.   

https://www.evernote.com/pub/villandra/testingforzika   Tests for the zika virus, those under development and those that have been approved

https://www.evernote.com/pub/villandra/vaccine  Efforts to develop a vaccine for Zika

https://www.evernote.com/pub/villandra/westnilevirus     Ariticles about West Nile virus

https://www.evernote.com/pub/villandra/wherearethemosquitoes    Assorted ridiculous half efforts to establish where Zika-bearing mosquitoes are in the United States

https://www.evernote.com/pub/villandra/whereiszika   Where Zika is in the U.S., where it is in south and central America and hte Carribean, including exactly where it is in Brazil and Columbia.

https://www.evernote.com/pub/villandra/yellowfever  Articles and books about yellow fever, which is closely related to zika and carried by the same mosqiutoes. 

https://www.evernote.com/pub/villandra/zika     Anything about Zika that couldn't be put in a category

https://www.evernote.com/pub/villandra/zikabudgetrequest   The budget request from the White House that Congress is not approving.  


Other Bibliography

Species Aedes Albopictus - Aedes Tiger Mosquito, at BugGuide.net  

Aedes aegypti and Aedes albopictus Mosquitoes in California. California Department of Public Health. Says it is updated weekly every Friday.  This is a map, that shows in what counties Aedes aegypti and Aedes albopictus have been encountered, and then in what city.   

Barrera, R (1996).  "Competition and resistance to starvation in larvae of container-inhabiting Aedes mosquitoes", Ecological Entomology, 21(2), 117-127.  

Bartlett-Healy, Kristen, et al.  "A model to predict evaporation rates in habitats used by container-dwelling mosquitoes", Journal of Medical Entomology 48 (3): 712-716.

Carrieri, Marco, Marta Bacchi, Romeo Bellini and Stefano Maini.  On the competition occurring between Aedes albopictus and Culex pipiens (Diptera: Culicidae) in Italy.   Environmental Entomology 32 (6):  1313-1321.  

 Gilotra, SK, Rozebloom, LE, Bhattacharya, NC (1967). "Observations on possible compettitive displacement between populations of Aedes aegytpi, Linnaeus and Aedes albopictus Skuse in Calcutta", Bulletin of the World Health Organization 37 (3): 437-46.

Halford, Bethany.  "Scientists scramble to develop tools, treatments for Zika virus".   C&EN  94(8), February 12, 2016, 94 (8).  Quotes Joseph M. Conlon, entomologist and technical advisor with the American Mosquito Control Association.   

Hornby, JA, Moore, DE, Miller Jr, TW (1994).  "Aedes albopictus distribution, abundance, and colonization in Lee County, Florida, and its effect on Aedes aegypti", Journal of the American Mosquito Control Association 10 (3): 397-402.

Juliano, SA (1998) "Species introduction and replacement among mosquitoes: Interspecific resource competition or apparent competition?", Ecology 79 (1): 255-268.

Juliano, Steven A (2004), "A field test for competitive effects of Aedes albopictus on A. aegypti in South Florida:  differences between sites of coexistence and exclusion?", Oecologia, 139(4), May, 583-593.

Juliano, SA, Lounibos LP (2005).  "Ecology of invasive mosquitoes:  Effects on resident species and on human health", Ecol Lett 8(5): 558-574.

Kaplan L, et al (2010).  Aedes aegypti and Aedes albopictus in Bermuda: Extinction, invasion, invasion and extinction.  Biol. Invasions 12:3277-3288.

Klowden, MJ, Chambers, GM (1992).  "Reproductive and metabolic differences between Aedes aegypti and Ae. albopictus (Diptera: Culicidae)",  Journal of Medical Entomology 29 (3): 467-71.  Literature review.  

Moore, CG, DB Francy, DA Eliason and TP Monath (1988).  "Aedes albopictus in the United States:  Rapid spread of a potential disease vector", Jouranl of the American Mosquito Control Association, 4 (3).

O'Meara, GF, Evans Jr, LF, Gettman, AD, Cuda, JP (1995).  "Spread of Aedes albopictus and decline of Aedes aegypti (Diptera: Culicidae) in Florida", Journal of Medical Entomology 32 (4): 554-62.

O'Meara, GF, Gettman, AD, Eveans LF Jr, and Scheel FD (1992).  "Invasion of cemeteries in Florida by Aedes albopictus", Journal of the American Mosquito Control Association,  March 1992, 8(1), 1-10.  

O'Meara, GF, Evans LF Jr., Womack ML (1997).  "Colonization of rock holes by Aedes albopictus in the southeastern United States", Journal of the American Mosquito Control Association, 1997 Sep, 13(3), 270-4.

Simard, Frederic, et al (2005).   "Geographic distirubtion and breeding site preference of Aedes albopictus and Aedes aegypti (Diptera:  Culicidae) in Cameroon, Central Africa",  Journal of Medical Entomology 42(5):  726-731.


This is the best article I have found on yellow fever.   It answers the question of why far more people in a community catch yellow fever far more quickly, than they catch dengue.  The answer is, they don't; 80% of a community may be struck by yellow fever at one time, and 90% by dengue, which is simply less deadly.   With both viruses, transmission rates can depend on what mosquito is carrying it; if a mosquito that mainly bites people, like Aedes aegypti, is the carrier the virus hits far more people at a much faster rate.

Rogers, D.J. et al. (2006).  "The global distribution of yellow fever and dengue", Advanced parasitology, 62: 181-220.


Contact me at tiggernut24@yahoo.com