Oops! Hopes for climate linkage to mosquito population increases dashed by new study

We’ve been told for years that climate change was going to unleash hordes of mosquitoes and disease upon us. For example, this article in Scientific American:

Mosquito-borne Diseases on the Uptick—Thanks to Global Warming

Infection rates of diseases like malaria, dengue fever and West Nile virus are likely to rise as a warming climate creates more mosquito-friendly habitats

Turns out that land use change and the decline of DDT are the biggest factors, while at the same time, climate change has little impact. This goes hand in hand with a study WUWT covered 3 years ago that suggests household size is the biggest factor in malaria, not climate.


Growing mosquito populations linked to urbanization and DDT’s slow decay

Rising temperatures due to climate change were found to have less influence on mosquito populations than land use changes and the decay of residual DDT in the environment

Culex pipiens, the northern house mosquito, is the most common mosquito in urban and suburban areas in North America. Mosquito populations have increased as much as ten-fold over the past five decades in New York, New Jersey, and California. CREDIT Ary Faraji

Culex pipiens, the northern house mosquito, is the most common mosquito in urban and suburban areas in North America. Mosquito populations have increased as much as ten-fold over the past five decades in New York, New Jersey, and California. CREDIT Ary Faraji

Mosquito populations have increased as much as ten-fold over the past five decades in New York, New Jersey, and California, according to long-term datasets from mosquito monitoring programs. The number of mosquito species in these areas increased two- to four-fold in the same period.

A new study finds the main drivers of these changes were the gradual waning of DDT concentrations in the environment and increased urbanization. The findings were published December 6 in Nature Communications.

The potential effects of climate change on the spread of insect-borne diseases is a major public health concern, but this study found little evidence that mosquito populations in these areas were responding to changes in temperature or precipitation.

“At first glance, recent increases in mosquito populations appear to be linked to rising temperatures from climate change, but careful analyses of data over the past century show that it’s actually recovery from the effects of DDT,” said corresponding author Marm Kilpatrick, associate professor of ecology and evolutionary biology at UC Santa Cruz.

Kilpatrick explained that the effects of climate change are expected to be seen at the edges of species’ geographic ranges, as species adapted to warm climates move further north and cold-adapted species retreat from the southern parts of their ranges. So a tropical species like Aedes aegypti, which transmits Zika, dengue, and other human diseases, could expand its range northward in the United States as temperatures warm.

“On the cold edge of a species’ distribution, temperature matters a lot. In Washington D.C., for example, where Aedes aegypti is not common now, it might become more common if the winters get milder. Whereas in Florida, urbanization and mosquito control efforts are more likely to be the dominant drivers of mosquito populations,” Kilpatrick said.

Urbanization is an important factor because it changes the species composition in an area, favoring the types of mosquitoes that live near and feed on people, such as Aedes aegypti, and causing other species to decline, such as those adapted to wetlands and other natural habitats.

Mosquito control programs continue to help limit mosquito populations in many areas, but currently available techniques are not nearly as effective as DDT was, Kilpatrick said. “Everyone knew DDT was an extremely effective insecticide, but I was surprised by how long-lasting its effects were. In some areas, it took 30 to 40 years for mosquito populations to recover,” he said.

More than a billion pounds (600 million kilograms) of DDT were used in the United States from the 1940s through the early 1970s. Its use was curtailed in the 1960s and finally banned in the United States in 1972 because of adverse environmental effects, especially on birds and other wildlife, as well as potential human health risks. Yet DDT was still detectable in soil cores as recently as 2000 in New York state, where DDT use was much higher than in New Jersey and California.

In all three regions, both mosquito abundance and the number of species decreased dramatically during the period of DDT use, then steadily increased as the amount of DDT in the environment declined. In New York, the researchers found, patterns of DDT use and its concentration in the environment could explain most of the long-term trends in mosquito populations. In New Jersey and California, however, the analyses showed that urbanization was also an important factor.

Average annual temperatures showed surprisingly little correlation with mosquito population trends. “Precipitation was more important than temperature, but land use was more important than either of those factors,” Kilpatrick said. “The long-term impacts of land use changes on ecosystems are sometimes underappreciated.”


The coauthors of the paper include Ilia Rochlin and Dominick Ninivaggi at Suffolk County Vector Control in New York; Ary Faraji at the Salt Lake City Mosquito Abatement District; and Christopher Baker at UC Davis.

83 thoughts on “Oops! Hopes for climate linkage to mosquito population increases dashed by new study

  1. It really is sad to see otherwise reputable scientists repeating the disproven lie that DDT had an impact on bird populations.

      • “Volume 103, Supplement 7, October 1995”
        I presume this is the publication date………..In which case, You’re citing 20 year old research.
        I’m not sure Google existed then, now they’re developing driverless cars, we have early stage vaccinations against cancer, AIDS is no longer untreatable.
        This is not good enough Griff. The world is moving faster than you can keep up. You NEED to cite last year’s research. With few exceptions, science is moving forward by the year, not the decade, or the century.

      • Griff, what passes for “fact” in your mind, never actually is.
        The only study that linked DDT to thinning shells in bird eggs was completely refuted.
        In every case, recovering bird populations were due to other factors.

      • For buzzards in Wales I’d say it was the latter, in the 50s and early 60s you’d see buzzards all the time then they virtually disappeared. Fortunately they’ve made a strong comeback.

      • 1. Example Falcons, eg. In Canada, not extinct (almost fully) as a result of the use of DDT. During this time entered into – to use, another highly toxic preparations used to make lures to catch fur animals and disposal rodents (UK). Those are eg .:endrin, oxydemeton-methyl, thiometon, etc. DDT has, of course, disadvantages. The main drawback is the simple structure – inexpensive production (…). Okay DDT is on Persistent Organic Pollutants, but it does not mean, that it is very harmful.
        2. Already in the 2010. P. W. Gething (Department of Zoology, University of Oxford http://www.nature.com/nature/journal/v465/n7296/abs/nature09098.html) concluded that: “… the proposed future effects of rising temperatures on endemicity are at least one order of magnitude smaller than changes observed since about 1900 and up to two orders of magnitude smaller than those that can be achieved by the effective scale-up of key control measures. Predictions of an intensification of malaria in a warmer world, based on extrapolated empirical relationships or biological mechanisms, must be set against a context of a century of warming that has seen marked global declines in the disease and a substantial weakening of the global correlation between malaria endemicity and climate.
        3. In my country scare, threatens by the appearance of Diabrotica virgifera – as a result of warming. I asked the question: where is the higher profitability (higher yields) maize cultivation: where there is Diabrotica virgifera – is a warmer climate, or where Diabrotica virgifera does not exist – is cooler climate?

      • Be careful of your wording.
        “DDT decimated UK bird” would have been a lie. The statement that DDT has effect on birds has been debunked.
        “DDT use decimated UK bird of prey populations” is more of an understatement. Mass-killing mosquitoes and other insects (DDT have no notion of “civilian” insects) starved and reduced number insect-eating birds and small mammals (but not to the point of endangering their population, there are so many of them …), which in turn was a even harder blow to bird of prey populations that depended on them (because birds of prey are not as numerous in the first place).
        DDT is best effective in homes, and there it doesn’t interfere with the whole nature.

      • 7 minutes after the first post Griff posts a link to UoCA (USA). Human lives don’t matter aye Griff. A paid shill indeed.

      • Another claim of a mad greenie. If you read the article, DDT’s residual effects are restricted to a small area around a production facility long abandoned.
        Was it cleaned up properly? Perhaps not, but shouldn’t you have concerned yourself with that? Jobs were lost, communities devastated and the green blobs solution?……well, it was not to provide a solution, only to direct the finger of blame.
        The continuing purpose of the destructive greens is to do nothing other than apportion blame. If you came up with solutions that were humanitarianly viable, we might not be sick to death of you.
        The green creed represents nothing but destruction. Not just to man, but to the environment. A perverse community that condemns others whilst your grow fat on human suffering.
        But the Robins are OK.

      • Robin’s are one of the group of birds that increased in population when ddt was used. The birds that did not increase were all raptors. The US CDC and Harvard Medical School recommend returning to the use of ddt to reduce the mosquito population.

    • Well according to this study, DDT is very effective against mosquitos.
      Ergo, use DDT against mosquitos, but not against birds where it is less effective.
      Personally, I can recall watching movies in school (Social Studies class; AKA History and Geography)
      In those movies, they showed third world people, men, women and children being blown from head to foot with DDT powder. They were all lined up as if they were going to get a Hydatids shot, and they poked a nozzle in the sleeves of shirts, and pants legs etc and blew them full of DDT.
      One would not describe those practices as a well designed mosquito control program.
      Just think; back then (1940s) a billion pounds of DDT would be enough for a few ounces for every person on the planet. Mosquitos don’t need near that much and they only need it where they are, not where everything else is.

      • I’ve seen those films too. they were treating body lice, not mosquitoes. It was an essential public safety measure, because soap and fuel to heat water were in very short supply after the war.

      • I think it’s time to re-examine–with experimental or other data-based tests–the actual effects, if any, of DDT on wild bird populations, and then to see if targeted application on mosquito-heavy environments can reduce the skeeter population without killing birds or other wildlife. I well remember, as a youth, being able to go outside for many days at a time with no mosquitos, once the DDT had been sprayed. I could actually work in the garden without putting on nasty, likely harmful, mosquito repellent. (Possibly this re-examination has already been done, in spite of the strong PC environment; I just don’t know of it.)

        • There is a long term study report done several years ago that basically said the presence of the DDT nasty chemicals in the systems of animals and humans caused no ill effects. Yes they accumulated. Within the last decade the WHO endorsed using DDT again for mosquito control as the most effective method.

      • The best practice on DDT I read, I think it was Bjorn Lomberg, was in paint.
        Mosquitoes like to land on surfaces, the paint binds the DTT and it does not get into the environment.
        Effective & simple.

      • “MarkW December 6, 2016 at 1:48 pm
        Griff and others have been assuring us for years that DDT has never had any impact on mosquitos.”
        As I understand, it was not DDT itself, it was the incorrect use of DDT in those affected areas where DDT was over used without proper basic prevention, ie, no stagnant water for the insect to breed.

  2. DDT has never been banned for use in fighting malaria… and indeed is in active use today for that purpose.
    “The signatories to the “POPs Treaty” essentially agreed to ban all uses of DDT except as a last resort against disease-bearing mosquitoes. Unfortunately, however, DDT is still a routine option in 19 countries, most of them in Africa. (Only 11 of these countries have thus far signed the treaty.) Among the signatory countries, 31-slightly fewer than one-third-have given notice that they are reserving the right to use DDT against malaria”

    • Sure, but did african government officials know that? Tanzania “lifted” a DDT ban in 2006
      “DAR ES SALAAM, May 8, 2006 (AFP) – Tanzania may lift a ban on DDT to boost its anti-malaria programmes, joining a growing number of African nations to consider the benefits of the controversial pesticide, an official said Monday.
      Minister of Health David Mwakyusa said the government was looking at legalizing DDT as part of a broader effort to eradicate the disease that kills an estimated 100,000 Tanzanians a year, most of them children under five.
      “We are looking at the possibility of using the insecticide which is effective,” Mwakyusa told AFP on his return from a just-ended African Union (AU) summit on HIV/AIDS, tuberculosis and malaria in Nigeria.”

    • Humans don’t matter to Griff, well maybe his family. I am confident he has never seen someone suffering where there was no help.

  3. I have it on good authority that there has been, and will continue to be an uptick in the population of one-eyed, one-horned, flyin’ purple people eaters, due to climate change of course. And they are definitely bad news.
    So there.

  4. The single most important factor in the prevalence of malaria, and other mosquito born diseases, is drainage.
    Two hundred years ago the western part of the State of Ohio at 40°N, where the winters are plenty cold and more than long enough, was a malarial swamp. Farmers showed up and drained the area and the malaria disappeared.
    When the Romans ran Italy, in the first 4 centuries of the Christian Era, they drained the Po Valley, and many low lying areas around Rome and Naples. They did not suffer from malaria. After the Barbarian invasions, the drainage works fell into ruin, and Italy had a Malaria problem, even in the middle of Rome. Russia was the scene of pandemic Malaria before the 20th Century.
    Tropical diseases are unrelated to the Climate, they are diseases of bad government and bad drainage.
    One of the worst crimes of “environmentalism” is the renaming of malaria swamps into “ecologically important wetlands”.
    Drain the swamps, not the metaphorical ones, the real wet ones, and you will control diseases.

    • My ancestors helped drain SW Ohio from 1803, which was a good thing. They also cut down the hardwood forests, which might have been less of a good thing, especially if you fancy roast passenger pigeon.

    • Sure, tell that to the folks in SE Asia, who are suffering respiratory illnesses and in some cases death due to the draining and burning of peatlands in Indonesia.

  5. Ozone, DDT, AGW…..the trifecta of artificially produced catastrophes that kill more people than they save.

    • Actuallly, ozone is completely natural, and AGW is just a fraud, so that just leaves DDT…
      Oh wait, were you being sarcastic ?

    • Actuallly, ozone is completely natural, and AGW is just a fr4ud, so that just leaves DDT…
      Oh wait, were you being sarcastic ?

      • Correct, but the catastrophes were man made/hyped for all three. The banning of DDT is responsible for many more deaths than any single other cause during the same period. Wars included. And they were all poor people/countries since the US and Western Europe had already eradicated their large mosquito populations using DDT.

      • Actuallly, ozone is completely natural, and AGW is just a fr4ud, so that just leaves DDT…
        Oh wait, were you being sarcastic ?

  6. Oboy, DDT! Another alarmist subject.
    If climate change science theory is robust and demonstrable in a logical self evident argument, and they have convincing data in hand that speaks for itself, why has no one actually presented it. Why do they hide from debate, why has the whole effort been to insult, have blocked from publishing, have editors of journals fired who do publish contradictory stuff, and why is there so much effort to adjust data to fit theory?
    Why do we only hear from useful idiots, trolls and social workers who wouldn’t know what to do with a quadratic equation or a Poisson distribution. Inquiring skeptics are to be found only among the brightest. It is simple minded and requires no ability to think in order to just be a believer.
    If CAGW is other than marginal, there would be no need for adjustment even for the reasons that Mosher states and a couple of dozen thermometers globally would serve. If we are in for several meters of sea level rise, why do we have to measure with a micrometer and make adjustments? Measure the damn thing in axe handles. I’ve got a CO/CO2 detector that doesn’t give a readout, it just shrieks get the he’ll out of here. If we had a detector for CAGW, it would be hanging there quietly and collecting dust. Come forward alarmists and convince us. Inquiring sceptics are more more intelligent tintelligent

    • “tintelligent”
      Good point though. Now the green blob moves to a 1960’s issue to prove a failing point. They will stoop further.

  7. Malaria used to be a problem in the USofA. It no longer is because of mosquito eradication. If we have an increase in the number of mosquitoes it’s probably because we slacked off on eradication.

  8. I guess these mosquito experts don’t read much history. In the summer of 1819 the Erie Canal was being dug through the Montezuma Swamp in upstate NY. Even in the midst of the Little Ice Age, the tough winter of 1818-1819, and just 3 years after the “Year without a Summer” the workers had to endure clouds of anopheles mosquitoes and the attendant malaria. Read: “Wedding of the Waters: The Erie Canal and the Making of a Great Nation”

    • Yes, Joe. Just visit the Canadian Shield forest areas to find out that mosquitos live well in cold climates too. They’ll carry you away like Studebaker Hoch (apologies to Frank Zappa).

      • And then there is the joke about the mosquito being the state bird in Alaska. I remember once being in Fairbanks in early-April, with the ground still covered with snow, but water was running in the creeks. The mosquitoes were already out in force.

      • The mosquito is a state bird in Minnesota. Like Canada, northern Minnesota is a haven for mosquitoes, especially in a wet spring. We were on a camping trip in the mid 50’s up near Ely. The folks had the bright idea to stop at an “unimproved” state park there. Got out of the car and everybody was immediately covered by about 10 mosquitos/sq. in. in about 10 seconds and the clouds were hard to see through. I think everybody agreed within 60 seconds that someplace else would be better. Fortunately we found a beautiful park with 200 ft red pines, a big lake with big white beaches that went out 100 yards, and showers. Shallow water is warm in Minnesota, but deep water is still COLD.

      • When we lived in Louisiana, we heard the scenario about two mosquitoes approaching a human. They were discussing whether to eat the person right there, or to carry him back into the swamp so the big boys wouldn’t take him away.
        Then there was the Louisiana method for killing mosquitoes: Hold about a 3′ x 4′ piece of half-inch plywood in front of you, with the wind behind you. The mosquitoes ahead of you, smelling your scent, poke their probosces through the wood; once you have enough of them, you take a ball-peen hammer and bend their probosces down to hold them to the wood, carry the wood to the creek, and drown the mosquitoes. (This, of course, was after the ban on DDT.)

  9. DDT was used after WW2 to treat typhus spreading lice in the vast number of refugees moving through Europe. The DDT powder was blown down the back and front of the top half of the body and down the trousers or skirt. Typhus killed many of the inmates who had survived the concentration camps as well as some of the medics who were caring for them. The French wouldn’t allow anyone across their border without a DDT treatment ticket.

  10. “..Rising temperatures due to climate change were found to have less influence on _________ than land use changes…”
    Think you could insert countless items in addition to mosquito populations.

  11. I have a friend who recently spent a year teaching at a university in Zambia. The university put him up at a nearby hotel. None of the hotel windows had insect screening (or A/C!). The claims of malaria re-surging in the US because of a couple of degrees of temperature change (if that) overlook the fact that the countries that are hot and have a problem with malaria, don’t have insect screens on their buildings and don’t have strong mosquito abatement programs.
    Malaria used to be endemic in North America. The early settlers in California would build their ranch houses at least a mile from the river to avoid the mosquitoes breeding in the river. We also have effective insect repellents now that weren’t available in the 19th Century. As usual, a lot of hand waving without looking at the bigger picture.

  12. Up to date information on work to eradicate malaria …
    Bill and Melinda Gates Foundation
    Malaria is preventable and treatable, and history shows that it can be eliminated. Less than a century ago, it was prevalent across the world, including Europe and North America. Malaria was eliminated in most of Western Europe by the mid-1930s; the United States achieved elimination of the disease in 1951.
    We have the opportunity to accelerate progress toward elimination in all countries by improving the delivery of existing interventions as well as developing new tools and new strategies that target not just malaria-transmitting mosquitoes but also the parasite itself, which can survive in humans for more than 10 years. By mobilizing the required commitment and resources, we can achieve global eradication and save many millions of lives.


  13. Dr. J, Gordon Edwards and Stephen Milloy put out a paper entitled ‘100 things you should know about DDT’, and all factually documented. It puts the boot to Griff and those like him. It was on the ‘junkscience’ web site, and is even more relevant today.

  14. Silent Spring, Coming of Age in Samoa, I could go on. It’s terrifying to think how many of the “classic” “factual” books of my youth did not conform to reality. But we’ve had a century of propagadvertising that should have taught us something, so why was An Inconvenient “Truth” successul?

  15. For those who believe that warmer winters really matter for mosquitoes, I can assure you that at least a few species dont’t know that: I have never seen so many mosquitoes as when I was serving my military duty in northern Norway. This place routinely have winter temperatures at minus 30-40 degC and records beyond minus 50. I can also mention that in the summer we had some days with more than +34 degC at the same location – life adapts, get used to it.

  16. Since Richard Nixon founded the EPA in 1970 – presumably as a cynical bid to greenwash his tarnished image at the height of the last eco-craze – the organisation has been run by a string of useless placemen and placewomen, who’ve done little that actually helps the environment, but plenty to burden the economy, consumers and business alike with more pointless regulation.
    Typical of these was its first Administrator William Ruckelshaus. A lawyer, by training, not a scientist, Ruckelshaus was the man responsible for instituting the America-wide ban on DDT. He did this on no scientific basis whatsoever. In fact, Judge Edmund Sweeney had presided over a seven-month EPA hearing, examining more than 9,000 pages of expert testimony, and concluded:
    DDT is not a carcinogenic hazard to man…DDT is not a mutagenic or teratogenic hazard to man…The use of DDT under the regulations involved here do not have a deleterious effect on freshwater fish, estuarine organisms, wild birds or other wildlife.
    Ruckelshaus, who had not attended the hearings or read the report, overruled him. Which probably made not much difference in the United States. But the knock-on effects of the near worldwide ban that followed meant that DDT could no longer be used to control mosquito populations, which in turn led to an explosion in malaria, causing the death of millions.
    H/T http://www.breitbart.com/environment/2016/12/06/donald-trumps-environmental-protection-agency-chief-could-be-his-best-pick-yet/

    • “Perry December 7, 2016 at 3:39 am
      DDT is not a carcinogenic hazard to man…DDT is not a mutagenic or teratogenic hazard to man…The use of DDT under the regulations involved here do not have a deleterious effect on freshwater fish, estuarine organisms, wild birds or other wildlife.”
      Exactly! It’s improper use that is the problem.

  17. Interesting. So DDT is still in the ground, stealthily killing mosquitoes but leaving human beings untouched. Which is not surprising because it never did anything bad to us. None of the readers here remembers the fact that by the end of World War II Europe was full of lice. DDT had been tried out on American troops in Italy and proved itself an effective lousekiller. When the war ended manufacture vof DDT went into high gear. It was used to dust whole populations in Europe, war prisoners, former slave laborers, and DPs in UNRRA refugee camps. I was one such DP dusted by an UNRRA team. For some peculiar reason, this did not give me cancer. As a matter of fact, not one of the millions dusted at war’s end in Europe was reported as having gotten cancer. This fact was well hidden during the DDT hearings when environmentalists implied that DDT causes cancer. Despite lack of proof, that was the final argument that made the ban on DDT official. As a result, millions of children in Africa have died of malaria carried by mosquitoes that would not be there except for the irrational DDT ban. The argument against allowing DDT to be used always hangs on the observation that DDT weakens the eggs of raptors which then do not hatch. An environmental argument that weights birds’ eggs higher than human casualties. The same stupidity that got the whole DDT ban started.

  18. Arno Arrak: “…the observation that DDT weakens the eggs of raptors which then do not hatch….”
    Several years before DDT was invented the British Ornithological Order published findings that bird eggs were weakening causing a decrease in population.

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