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Question of the Week © 2017 Mike McGrath
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Special Report: Moderating Menacing Mosquitoes
As we learned on today's very special program, it isn't just the 'new' Zika virus we need to fear. We'll also see the return of old favorites like West Nile and other mosquito-carried ailments with the arrival of the warmer weather we're otherwise looking forward to. But as Mike and Rutgers Entomologist Dr. Dina Fonseca stressed during the show, you can greatly diminish the number of mosquitoes that would otherwise plague your backyard this summer by taking action now.
Because if you knock down the numbers of the first couple of generations, you'll get the math on your side for a change—the mosquito population will still grow exponentially, but if that first number is two as opposed to two thousand, you're on your way to a relatively bite-free summer. Step one: clean up any trash in your yard; mosquitoes can breed in bottlecaps, plastic bags and other places you might not expect.
But as Dr. Fonseca has been explaining, there are two different types of mosquitoes to protect against—and the more recent arrival, the day-flying Asian 'tiger mosquito' Aedes has a very different life cycle than the 'old friends' we're used to. These aggressive day-time biters overwinter in the egg stage; but those eggs aren't floating on the surface of standing water like the eggs our 'old school' mosquitoes will soon be laying. They're attached to the insides of water-holding objects like wheelbarrows, ready to be activated when the weather warms and the water level rises enough to reach them after a rainfall.
So just dumping out wheelbarrows, recycling bins, children's toys and the like isn't enough with these terrors. You also have to scrub the eggs off of the inside of any items that can hold water to destroy them. (And then, of course, make sure those containers stay dry.)
Or, if you want a no-scrub option, you can pour BTI granules into any containers that are holding water or could hold water. If you go that route, I'd even suggest topping off the containers, so the eggs are subjected to the BTI right away.
(This is where we need to remind people that BTI (a naturally occurring soil-dwelling organism) is toxic only to creatures in the fly family. It has no effect on fish, birds, pets, people, toads, etc. OK?)
Now, the 'Culex' mosquitoes we all grew up with—the ones that mostly bite when day changes over into evening—are already among us in the adult form. The last females of summer hibernate in sheds, garages and other protected areas, emerge on the first nice day looking for a blood meal and then seek out standing water in which to lay their eggs.
The old advice was to dump any water on your property to deny those mosquitoes that breeding ground. And that's still excellent advice. But this is another instance where you can use their breeding water against them by lacing that water with BTI dunks or granules, which will prevent those eggs from becoming biting adults. Deliberately put out standing water laced with BTI, and all of the females near your home will lay their eggs in the water but no new mosquitoes will be born.
Now: I'm not normally surprised by anything I hear during an interview, but Dr. Fonseca revealed something on the show that I clearly had not previously known about mosquito behavior. And I should have figured it out on my own, because I did know that male mosquitoes are actually pollinators. They don't take blood meals, and so get all their energy from the nectar—and maybe the pollen—of flowers. But Dr. Fonseca explained that biting females (who I had only thought of as blood suckers) also feed on the nectar of small-flowered plants for energy.
And those are the exact same kinds of plants we're always telling gardeners to use to lure pollinators and beneficial insects to their backyards—especially in the Spring; the same time of year we're telling everybody to prevent future mosquitoes!
Luckily the answer is once again BTI. Place small containers of water near your earliest-blooming flowers, treat the water with BTI, and the females who visit the flowers will lay their eggs in this convenient water source, but no adult mosquitoes will emerge. Then do the same thing in the Fall, when day-fliers are laying their over-wintering eggs.
So, let's review:
• Empty and scrub plant saucers, outdoor children's toys, recycling bins; anything that can hold water. And then don't let those containers fill up with water again!
• Clean up any small trash in the yard. One of Dr. Fonseca's colleagues has shown that the Aedes mosquito (the day flying Asian Tiger kind) can go from egg to adult using the amount of water in a bottlecap!
• Put containers of water laced with BTI around your home and freshen up the BTI as directed. And make sure that some of those traps are near plants with small flowers.
• And if you have gutters, clean them out as well. They are the great unseen breeding ground. And they don't even have to be clogged to be dangerous; just a low spot that doesn't drain well can breed these ancient disease-carrying enemies of mankind.