Photo courtesy of Benimoto at Flickr.com.
If your flowers or vegetables are suffering from an attack of aphids, consider adding aphid midges to your garden’s beneficial insect mix. The larvae of these tiny, nocturnal cecidomyiid flies (Aphidoletes aphidimyza) chow down heartily on more than 60 species of aphids, hence their nickname. They especially love potato plants and cole crops (cabbage, broccoli, Brussels sprouts, cauliflower, etc.), but will happily haunt orchards, ornamental backyard gardens, and even greenhouses. In fact, they’re very important as a control species in organic greenhouse cultivation.
These little mosquito-like mites, which might measure about 1/16 of an inch across on a good day, are extremely effective at zeroing in on aphid colonies and zapping the nasty little critters: a single aphid midge larva needs at least seven aphids to complete its larval cycle of 1-2 weeks, but may consume 80 or more—and they tend to kill more bugs than they actually eat, which adds to their allure.
Photo courtesy of ((brian)) at Flickr.com.
It’s possible to attract aphid midges to an American yard or garden by planting their favorite crops, as they’re native to most of the continent and common throughout their range. Particular favorites include sweet clover, sweet alyssum, yarrow, and mustard, and they’re also partial to herbs like dill, parsley, and cilantro. But attracting aphid midges can be a hit or miss process, so it’s usually much easier to simply buy some from a supplier of beneficial organisms. They’ll be shipped to you as larvae in a bedding of moist material such as fine sand or vermiculite, which you should spread around the bases of your plants as soon as you receive it.
Adult midges will require a source of honeydew (preferably the flowers mentioned above, though some trees might do in a pinch), and will start laying eggs within a few days of maturity; the eggs will hatch within 2-4 days. You’ll know the larvae are in action when you start finding aphid mummies (tiny blackened aphid husks) clinging to your plant leaves—and, of course, fewer aphids all around.
One note of caution: be extremely careful with pesticide sprays in your garden if you’re using midges to control your aphids, because the adult midges are quite susceptible to most sprays, even those made with organic ingredients. If you manage your aphid midges carefully, they’ll produce about six generations a year, and will overwinter in your garden to appear the next spring.
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