Its Time to Trap Your Mosquitoes

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Q. Last summer I organized 150 of my neighbors to participate in mosquito control using the BTI strategy for which you credit Howard Garrett, "The Dirt Doctor" down in Texas. Each neighbor put out buckets of water treated with a piece of BTI dunk, which was replaced monthly. The first half of the summer was relatively mosquito free. In August the system started to fall apart when people became lax about replacing the dunks. All in all, it was a good first season, and we are getting ready to try it again this year."

---Connie in the Mt. Airy section of Philadelphia; "right near the Lutheran Seminary, where Mike hosts the annual Empty Bowl dinner every November."

A. Ah yes—the Empty Bowl dinner; a great way to fight homelessness and hunger in your community. You enjoy delicious soups donated by local restaurants and then get to take home a soup bowl that was hand-made by school children and area potters—as a reminder of the bowls that remain empty in America. (Or that you helped fill some bowls by attending.) Empty Bowl events are held all over the country in November; please attend if there's one near you! (Here's a neat one minute clip of Mike at the event in 2010.)

Anyway—back to using BTI to trick mosquitoes. Connie is correct: I got the idea from my good buddy Howard, a Texas based organic advocate. And we are both really happy to hear that somebody picked up this idea on such a large scale. When we first starting talking about this strategy two seasons ago, my hope was that a good number of people would do it individually—but when over a hundred households join in, you're talking about knocking the mosquito population down in an entire neighborhood. (And hers is a good neighborhood to do that knocking down in, as the nearby Wissahickon Creek provides lots of breeding ground for mosquitoes, especially after the wet winter we just had.)

Let's repeat the basics of the plan and explain the mosquito biology we are using to our advantage:

Every Fall, the last generation of mosquitoes seeks out places to hibernate for the winter—outdoor structures, crawlspaces and other protected areas. Those mosquitoes come out of hibernation with the first warm weather, and the females have to find a blood meal fast—that's you, me, a pet or a wild animal. And then those females have to find standing water in which to lay their eggs.

…Which is why we're always told to check our property this time of year and empty out things like buckets, wheelbarrows and anything else that's holding water. Something as small as a cat food can that fell out of a recycling bin can serve as a 'breeding pool'.

And let's not forget our gutters; they're an unseen breeding source—which is why I make it a bigger point to check them in the Spring than in the Fall. If you're a mosquito, a clogged gutter is like one of those cheap motels that charges by the hour. So check your gutters, America!

But in addition to that 'gut check', Howard and I have been promoting the idea of deliberately giving mosquitoes what seems like a perfect source of standing water instead of making sure your landscape is dry. It just might be the single cleverest piece of pest control advice ever!

Now, most people are familiar with the 'dunks' that Connie and her neighbors are using; the little doughnut-shaped things sold in packs in virtually every hardware and home store in America, with a big picture of a mosquito on the front so you know what they're for. You toss them into ponds or abandoned swimming pools or whatever and they prevent mosquitoes from using the water for breeding for about a month.

Female mosquitoes will still lay their eggs in that convenient water source, but their larvae will not be able to develop into biting adults. Treat all the water in a given area and the females in that area will keep laying eggs that never grow up. And BTI is totally safe to use. It doesn't affect people, pets, birds, bees, toads…

A naturally-occurring soil organism that was originally isolated in Israel (that's what the I in BTI stands for), it only prevents the successful development of members of the fly family that breed in water—like mosquitoes, blackflies and blood-sucking gnats. It affects nothing else. That's one of the big positives; you can treat areas that stay wet in the Spring with BTI, and frogs, toads and lightning bugs will still be able to breed there. Just not mosquitoes.

But you can also buy BTI granules, and I suspect they might work better than busting the dunks up into chunks. You can pour some of the granules into a bucket of water you'll leave outside, sprinkle some into those ubiquitous cat food cans, and shake some out onto areas of your property that stay wet in the Spring. Mosquitoes only need about ten days to go from egg to adult, so if they're left untreated, the temporary 'vernal pools' of Spring snow melt that occur in so many regions can breed a lot of skeeters before they dry up.

But if you clean out your gutters and set BTI 'traps' all around your property, you'll knock down that all-important first generation—the females that have been waiting all winter to nail you. And that can really make a dent in the season-long population.

Oh, and why do I keep specifying "females"?

Because only female mosquitoes are blood-sucking fiends. As with humans, the males are harmless gatherers of pollen, flitting from flower to flower…..

A-hem.