BTi and The Mosquito Dilemma


Unless you’re a bat or a dragonfly, July and August and even September are not comfortable times to be in my garden. When these months hit I wear a suit of long pants, high socks a long sleeve shirt and a heavy dousing of bug repellent. But no sooner am I pulling up that quackgrass, when I feel the itch. First one, then another, then then the whole swarm catches on to the delicious snack. Me.

The main advice about this problem is remove anything that collects even the tiniest amounts of water which includes gutters, rain barrels, containers, etc. The other advice is to use BTi or Bacillus thuringiensis subspecies israelensis, a natural bacterium found in soils and thought to only affect mosquito, black fly and fungus gnat larvae. At least this is what the EPA says as well as many other sources but a study was done in 2010 involving house martins that concluded evidence of effects further up the food chain. The study found the breeding success of house martins was significantly less in areas treated with BTi than in areas untreated with BTi. Loss of mosquitoes, the birds preferred food source, was found to be the cause.

I’ve heard Mike McGrath, the gardening guru from Philly talk about using BTi dunks to make mosquito killing traps. That sounded great at the time. But as it’s now winter and I’m not out in the hot sun getting massacred, I’m thinking that maybe the mosquitoes are here for a reason. Maybe instead of trying to completely annihilate them as we humans like to do with anything that “bugs” us or our stuff, maybe we should think about these problems from more of an ecological perspective.

It may be better to think more in terms of balance rather than control, coexist rather than divide, proact rather than react. Maybe we get ourselves so focused on the problem we don’t see the solution. Inviting animals and invertebrates that eat mosquitoes might be the best solution we have. Bat houses and mosquitoes invite bats. Water and mosquitoes invite dragonflies, frogs and birds. Bats, dragonflies, frogs and birds mean a stronger ecological system. A strong ecological system means a better chance of long term survival for us all.

I would say I probably have too many mosquitoes and this year I’m going to work on that but I’m not going to go extermination crazy. I’ll use small pieces of BTi mosquito dunks in my rain barrels only because it’s the only way of mosquito proofing them. When mosquitoes are bad, I’ll stop using cardboard that collects water and refresh bird baths twice a week. And I’ll wear my mosquito protection suit. While it’s not exactly the best case scenario for me (at the moment), it’s the best case scenario for ecology and that, I think, is the best case scenario.


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