I’ve never met anyone with any compassion for the mosquito. Besides serving as food (not often enough) for birds, bats and frogs, their only asset is their role as pollinators. Now more than ever, especially as gardeners, we need to be aware of the diseases mosquitos spread and how to avoid them while managing not to poison ourselves and allied insects.
Why should the mosquito situation be of more concern now? The way I figure it, a number of factors increase the likelihood of exposure to mosquito-borne diseases.
The first reason is global warming. It doesn’t matter whether you think it’s caused by human meddling or is a natural process — the earth, on average, is warming. Wetter, warmer conditions are ideal for mosquitos and will allow them to spread into previously cooler, drier territory.
While we won’t see palm trees in Antarctica any time soon, it’s likely new species of mosquito will be able to spread into new geographical areas, along with a longer mosquito season.
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Second is globalization. This has been going on for millennia really, with a relatively recent exponential increase in global travel and commerce. Mosquitos can travel with us on planes, on our produce, in plants, and in shipments of used tires. A person infected with a mosquito-borne illness can inadvertently spread the pathogen; if mosquitos feed on the individual, the illness re-enters the mosquito population, then comes back to humans.
Third is resistance to insecticide. This is a two-pronged issue. First, mosquitos themselves can adapt to survive pesticides. This kind of resistance happens to all types of organisms. Think of bacteria and their ability to evolve resistance to antibiotics.
The second prong is our own reluctance to use insecticide. This is not a bad thing, really. Insecticides have caused a world of hurt to our health and environment. However, thoughtfully, strategically applied insecticides can save lives. A love of nature, gardening and the outdoors also puts more of us out there among the hungry mosquitos.
They aren’t all dangerous — only 13 of the approximately 80 species of mosquitos found in Florida are considered vectors of disease (the species that transmit it) — but the bad guys (girls, actually) are pretty nasty.
One species a little easier to recognize is the Asian tiger mosquito ( Aedes albopictus), so called not for its ferocity but rather its black-and-white-striped legs.
A close relative is the frighteningly named yellow fever mosquito ( Aedes aegypti), which also spreads the virus causing dengue fever, and of course yellow fever.
Both species can also spread eastern equine encephalitis, and are active daytime feeders . Multi-talented, these mosquitos! But there’s more.
Until 2009, Dengue fever hadn’t been seen in Florida for 70 years. Then in 2013 we saw multiple outbreaks in Stuart, Florida. The suspected culprit was Aedes aegypti.
And though we don’t hear too much about West Nile Virus these days — the Florida Department of Health lists no human cases so far this year — a new threat has appeared: chikungunya virus. It’s been known in Africa and Asia for decades, and recently made news in the Caribbean. It wasn’t difficult to jump from there to South Florida, where the mosquitos that spread it are already well established: our old friends the Asian tiger and yellow fever mosquitos.
The Florida Department of Health, as of Aug. 9, reports so far for 2014 only one case of dengue acquired locally, and four local cases of chikungunya. All other cases were acquired from travel abroad.
Let’s not forget malaria. Though not caused by a virus, it’s nevertheless mosquito borne thanks to the Anopheles genus of mosquito. Most all recent cases of malaria were acquired abroad, though the species that transmit it do live within the United States, so it is a threat to be monitored. Thankfully, these numbers are all remarkably low. We must be doing something right!
The University of Florida’s Mosquito Information Website exposes some mosquito myths: ultrasonic devices, eating garlic, carrying fabric softener sheets or using bug zappers are not known to deter mosquitoes. Save your money and time.
So what can we do? While there’s no easy answer, it’s best to avoid exposure in the first place while depriving mosquitoes of convenient places to breed:
• Wear long pants and long-sleeved shirts outdoors, particularly at dawn and dusk — not a pleasant prospect in summer.
• Drain standing water. It can accumulate in the oddest of places: garbage cans, birdbaths, folds in tarps over BBQs, etc. Mosquitos love laying eggs in or near water inside old tires. They heat up nicely in the sun and act as incubators. Another place to watch is empty flowerpots, especially plastic ones with areas that don’t drain. Hose out your bromeliad tanks, as they, too, can harbor larvae.
• Use screens on open windows.
• When outdoors, use a repellant recommended by Floridahealth.gov: products containing DEET, picaridin (aka icaridin), oil of the lemon eucalyptus, and IR3535 have been proven effective as insect repellants. Picaridin, unlike DEET, doesn’t dissolve plastics. Apply repellants over sunscreen, if you are using both. If you spend lots of time outdoors, consider permethrin-treated clothing and camping supplies, used by the military for many years. The treated fabric repels insects even after washing.
• If you travel to a region where exposure to mosquito-borne illnesses is likely, tell your doctor before you go. Be extra careful to wear appropriate protection and ensure window screens and mosquito nets are properly used while traveling.
We have to use our brains to beat the bugs by minimizing exposure, being on the lookout for potential breeding areas and eliminating them.
More information on combating mosquitos can be found at:
The Florida Mosquito Database: http://mosquito.ifas.ufl.edu/FMD/Florida_Mosquito_Database.html
University of Florida’s Medical Entomology Laboratory: http://mosquito.ifas.ufl.edu/Index.htm
Centers for Disease Control and Prevention: www.cdc.gov/ncezid/dvbd/