Tuesday, May 07, 2013

Miniponds as Mosquito Traps


If you happen to have a small pond in your yard, without any fish to gobble up the mosquito larvae, it's time to do some low-calorie dunking of donuts. The active ingredient in these "mosquito dunks" is BTI, short for Bacillus thuringiensis israelensis, a natural bacteria that kills mosquito larvae that ingest it. You break off a chunk of the donut, according to the size of the pond, and the donut slowly releases the biological control into the standing water. They are available at local hardware stores, and are best applied to water before the mosquitoes show up, so the active ingredient has time to disperse into the water.

Though people tend to think any standing water breeds mosquitoes, a backyard minipond with this BTI applied essentially becomes a mosquito "trap", sabotaging the breeding efforts of whatever female mosquitoes visit the pond to lay eggs. This occurred to me about fifteen years ago, and I heard a similar contention expressed when I happened upon the radio program "You Bet Your Garden" a few weeks back.

There are other natural predators of mosquito larvae, such as predatory dragonfly larvae, water striders, and a couple types of soil fungi. These various controls may or may not be present, making for a lot of variation in which ponds will breed mosquitos.

The package gives the green light for putting these in animal watering troughs, which I'm taking to mean they're okay for our ducks' habitat. Dunking is recommended once every month or so during the growing season.

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