Beneficial Insects: Not All Bugs are Bad
(Page 4 of 8)
April/May 1995
By John Vivian
And, try not to harm the most swattable "bees" you come across ...not bees at all, but big-eyed "hover flies" that suspend themselves just in front of your eyes and dart in to taste your skin when you're all sweaty from outside work. They are harmless but must think you and I smell like aphids, because they lay their eggs on aphidcovered plants. The young feed greedily upon the bad bugs till its time to pupate in the soil.
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Other Controls for Aphids, Mealybugs, and Scale Insects
Hover flies can't kill all the aphids; firstgeneration female aphids can clone themselves parthenogenetically (no males involved) in huge numbers in little time. To keep them off the young garden vegetables, I plant perennial peony bushes around the garden and annual nasturtiums in the rows. Stems of both plants are always harmlessly covered with black and green aphids—laid by flying females and placed there by sugar ants that tap the honeydew the tiny bugs produce. The ants seem to prefer running their aphid herds on nasturtiums and peonies to infesting my garden peas. But I've never been able to keep the aphids from killing early-planted fava or broad beans. Native to Europe, broad beans have never naturalized in North America and—in my cool New England climate at least—aphid-herding ants or flying-stage aphids or both seem to prefer this foreign exotic to anything! In their place I just plant extra limas and wait a while.
For aphids, mealybugs, scale insects, and the other soft-bodied insects and larvae that are attracted to garden plants, you can field a whole army of insect and arachnid predators. Brown and green lacewings ( Hemerobius and Chrysopa species) are related families of very common half-inchlong insects with four long, rear-facing, filmy wings with no wind covers to hide them. Both adults and larvae are such voracious predators of soft-bodied insects that the immature are called "aphid wolves" and "aphid lions." Different species occur throughout the continent, and one or more is flying from spring through summer. The best things you can do to encourage them is to avoid all poisons in the garden and not use an electronic "bug zapper" or leave the barnyard light on at night. Soft-bodied as their prey, they are highly susceptible to insecticides. And, like night-flying moths and june bugs, they will foolishly batter themselves to death on a night lamp.
Everybody's favorite insect is the ladybug (the Coccinellida family). The many species of these orange, yellow, or red, black-spotted (or black with colored spots), round-bodied little insects and their larvae are savage predators of softbodied garden pests. During the European Middle Ages, they were so helpful in controlling grapevine pests they were dedicated to "Our Lady," thus the name.
In snow country, the final hatch of adults swarm and overwinter together in sheltered places to renew the race next year. Large numbers always choose to hibernate under the clapboards on the north wall of my old house. On sunny latewinter days, they'll crawl out to wander around sleepily inside the storm windows. To preserve their energy for the coming spring's gardening, I collect them, put them in the fridge in a canning jar (topped with mesh screening held on with an elastic band so air will circulate and they'll not suffocate). I release them a little later than they'd emerge naturally—after the new lettuce and sweet peas are up and attracting aphids.
I understand that a new immigrant species from Asia (red with black spots and a white "M" on its forehead) is a little too chummy in its winter-hibernating style. Come fall, one of them will select what it feels to be a nice wintering location, but one that you may not like ...under the dining room table or in your bureau sock drawer, for example. Then it secretes a pheromone—a chemical signal—that invites hundreds of its brethren to pile on for the winter. I've not experienced them yet, but if you should, just lay your hands on a large jar or two, cover it with screen, and keep the lot of them cool enough to remain dormant till spring.
Western species of both lacewings and lady-bugs are sold commercially. Lacewings are reared in bug labs and ladybugs are collected from overwintering caves high in the California Sierras. In my experience, they are programmed to take flight and disperse as soon as they are released. Fine for greenhouses, but I doubt that they stick around your garden long enough to do your pea vines much good.
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