Q. I live in a row house with a small yard and raised bed vegetable garden that were completely overrun by Asian Tiger mosquitoes last summer. And I expect it to be just as bad if not worse this year. I am one of those people mosquitoes seem to love, and they attack me the minute I set foot in the yard. Even when I wear pants, long sleeves and a high concentration of DEET or Skin so Soft, I still get bit—and in broad daylight by these Asian Tiger buggers. The solutions I see online all involve putting stuff in the water where they lay their eggs, but we make sure not to HAVE any standing water on our property. Is there any way to combat these mosquitoes when you can't find their water source? If I garlic spray my yard, will they let me garden in peace? I'd also love to be able to sit on our deck and enjoy a nice glass of wine without being overpowered by the scent of bug repellant. Any suggestions would be greatly appreciated. Thank you,
---Aimee in Ambler, PA
A. I'm not surprised that the chemical repellant DEET doesn't protect you. Chris River, one of our great volunteer researchers, just sent us an article from a peer-reviewed journal revealing that mosquitoes quickly become resistant to DEET after their first exposure. (The research, performed by Dr. James Logan from the London School of Hygiene and Tropical Medicine, was published just last month.)
And even if it WAS effective, I'd still think it was madness to use DEET!
DEET is a potent nerve toxin that is absorbed through your skin and exits your body via your liver and kidneys. If you want to use a repellant, several non-toxic, natural products have proven to be as effective as DEET in controlled medical studies (the dreaded arm placed into the box of hungry female mosquitoes). The brand names and study citations are listed in this previous question of the week — as are the details on using herbs that also have a high degree of repellency, like catnip and lemon thyme.
And Dr. Logan's groundbreaking new research leads me to add a new suggestion—that you rotate a number of different natural repellants so that mosquitoes don't develop resistance after repeated exposure, the way they have with DEET. (Oh, and Avon's "Skin so Soft" is not something I'd suggest in the rotation; it totally failed in those controlled studies.)
But outdoor garlic sprays are highly effective. If you spray concentrated garlic oil (available from a variety of sources under a variety of brand names) on your backyard, it should stay free of mosquitoes, ticks and other nasty biting things for two to six weeks, depending on air temperature and rainfall. And a fan blowing from behind will allow you to sip that Chablis on your deck without being Cha-blitten; mosquitoes are not strong fliers.
Research has shown that mosquitoes do prefer certain people over others, so you 'mosquito magnets' might want to check out "Insect Shield"; a company that sells clothing treated with insect-repelling permethrin, a chemical version of the natural insecticide derived from chrysanthemum flowers. This is one of the few instances where I think common sense allows use of a chemical—you don't spray it on the environment, you don't spread it on your skin, and the protection lasts for months or years, even with normal washings. And it's effective against ticks as well as mosquitoes, which DEET is not.
I also want you to make sure that you're checking your gutters when you insist you have no standing water around. Clogged gutters are the great unseen mosquito breeding area.
And now we get to the really cool stuff; a new way to attack mosquitoes, instead of just repelling them. It involves the all-natural larvacide BTI, which I've been recommending to prevent mosquito breeding in standing water for over a decade. One of the many forms of the naturally occurring soil organism Bt, BTI prevents mosquito larvae from breeding in water—which is the only place they can breed—without harming any other form of life.
If you live next to a pond or such, you toss a couple of BTI dunks in the water once a month. If an area of your lawn stays wet deep into Spring, you scatter BTI granules in the damp areas once a month. Female mosquitoes will still lay their eggs in these wet areas, but no adult mosquitoes will emerge.
And my organic counterpart down in Texas, Howard Garrett "The Dirt Doctor", wants everyone to take that basic idea up a notch. Instead of dumping out all your standing water, Howard says to leave it be. And put out lots MORE standing water. Fill your wheelbarrows; leave out dozens of cat food cans filled with water; buckets; dishes, bowls….
And then treat them all with BTI. All the female mosquitoes in your area will flock to these easy breeding sites and lay their eggs. But no new generations will arise from that water. The more people who do this, the fewer mosquitoes we'll have.
This is an idea that's elegant in its simplicity—and finally, a way to fight back against these nasty biters!
(Note: All "Bt is not BTI. There are several different varieties of Bt on the market, and the old original basic one (used to kill pest caterpillars) will not affect mosquitoes. So if you're the least bit confused, read these previous questions of the week on Bt and BTI.)