Why Mosquitoes and Mild Winters Don't Mix

Learn how to handle an early mosquito hatch.

March 27, 2012

When it comes to mosquito diseases, West Nile virus tends to get all the headline-grabbing attention. It's probably the most common disease spread by the little bloodsuckers, at least here in the U.S. Incidences of West Nile peak in August in September, when mosquitoes transition from sucking the blood of birds (their meal of choice for the early part of the summer) to sucking the blood of people and other mammals.

But according to a new study published in the journal Biology Letters, the mild winter we've just had may speed up that transition, and that could lead to a higher incidence of mosquito-borne diseases this year.


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The authors trapped one particular mosquito species, C. erraticus for eight years, testing the DNA of the blood in the mosquitoes they trapped so it could be traced back to the source. In warmer years, the mosquitoes transitioned from biting birds to biting mammals in May or June, whereas in cooler years, the transition happened in August and September.

With a warm spring arriving on the heels of a mild winter this year, mosquito populations are likely to sprout earlier and thus transition to a human-based diet earlier than they normally do. And it's not just West Nile virus that they could bring with them. The species of mosquito studied here carries the uncommon but fatal disease eastern equine encephalitis. Carried by birds, the disease spreads to humans after they are bitten by a mosquito that has also bitten an infected horse. Although just a few cases are reported in the U.S. each year, 33 percent of infected people die from it, and it can leave survivors with significant brain damage.

Photo: (cc) dr_relling/Flickr

No need to shore up your supply of toxic mosquito repellents, though: The chemicals used to kill mosquitoes can be just as threatening as the diseases they carry. To keep your home mosquito free during what could be a bite-riddled summer, take these steps:

• Call your neighbors. Neighborhood mosquito-abatement programs, handled by your municipal government, involve spraying iffy pesticides throughout your neighborhood from trucks or airplanes, whether you know it or not. Most of the time, they use synthetic pyrethroids, hormone-disrupting pesticides that can waft into your home, and according to Jay Feldman, executive director of the National Coalition Against the Misuse of Pesticides, those neighborhood sprays aren't effective because they don’t come into direct contact with mosquitoes, which is the exposure it takes for them to die. To find out what mosquito-spraying policies are in your city, just search online for your city or county and add "mosquito abatement district." Then contact your municipal government to petition for safer methods, like using beneficial bacteria in lakes and ponds that kill mosquito larvae.

• Clean up your backyard. Cover, clean, or eliminate anything that collects standing water (the ideal breeding ground for mosquito larvae), for instance, empty trash cans and lids, kiddie pools, rain barrels, and birdbaths. And learn how to make songbirds and bats fall in love with your backyard. They're the natural predators for mosquitoes.

• Ditch DEET and pesticide-treated clothing. Unless you're hitting the tropics or some other area known for voracious skeeters, you don't need to resort to toxic, nerve-damaging DEET or clothing treated with those same hormone-disrupting pyrethroids. For ideas, check out our roundup of plant-based mosquito repellents without DEET.

We Like This! — Organic Mosquito Repellents, from Rodale's

Intelligent Nutrients
Bug Repellent Perfume Serum
Tansynella Bug Repellent Oil
Buzz Spray Bug Repellent

Photo: (cc) dr_relling/Flickr