Bug Vs. Bug

By Chris Clarke

A few years back, I walked into my garden to find my corn was covered with ugly black aphids. I mean covered: nearly every square inch of leaf smothered by insects. They had totally overwhelmed my poor plants, sucking the lifeblood out of them.

Steeling my nerve, I did what every red-blooded organic gardener should do: I went camping for a week. When I returned, the aphids were under control. A few live ones here and there, but most of them either dead or gone.

A miracle cure? You bet: the miracle of the food chain. Next to the corn was a huge patch of fennel in full bloom. Fennel blossoms attract all kinds of insects, including some that either eat or lay eggs in aphids. The buzzing mass around those pale green flowers was all the insect control my corn needed.

Beneficial insects, which eat or otherwise control pest insects, can be a gardener's best friend. You can put beneficial insects to use in your garden, too. Here's how to start:

• Don't spray. You wouldn't want to eat food that's dripping with toxic chemicals, and neither do predatory insects. What hurts the aphid hurts the ladybug as well.

• Use beneficial insect-attracting plants. Some plants' blossoms attract all manner of beneficial insects. Fennel is just one: You may already be growing a beneficial insect plant without knowing it. Cilantro or coriander is one of the best. Once you've harvested those aromatic leaves for your stir fry - let the plant flower. Alyssum, sold in almost every nursery in America, is another. If the plant is in the celery family, (fennel, cilantro, dill, chervil, celery), its flowers attract beneficials. If a blossom smells like honey, (e.g. alyssum), you'll find beneficial insects coming to dine on its nectar and staying for the main course: your insect pests.

• Tolerate a few pest insects. This seems counterintuitive. The point is to get rid of the things, right? But look at it from the point of view of the beneficial insect. You're a bug that eats cabbage loopers. Would you bother with the pest-free cabbage patch? No, you'd set a course for the garden that had some nice fat caterpillars for you to eat. A handful of pests won't ruin your garden, but that handful will attract beneficial insects.

• Import beneficial insects. OK, you've done everything right: stopped spraying, planted a nice row of alyssum, and tried to turn a blind eye to the cabbage loopers eating the outside leaves of your heirloom cauliflower, but they're starting to eye the inside leaves. Time to call for reinforcements.

Many garden stores sell ladybugs and praying mantises. They're fun, but they aren't always the most effective helpers. Ladybugs tend to fly away after they eat your aphids, and given mantises' habit of eating their own kind (in addition to everything else), you're likely to end up with just one very large mantis a few weeks after the egg case hatches out.

Serious insect-using gardeners rely on two main types of insect: lacewings and wasps. Lacewing adults are tiny, delicate-looking things that literally wouldn't hurt a fly. Their larvae, on the other hand, look like a cross between alligators and armored personnel carriers, and they eat any insect in their path, whether mealybug, aphid, scale or what have you. Once imported into your garden, a good-size patch of attractant plants will feed the adults, and you'll always have enough larvae to go around, unless you spray.

You might be wondering what kind of person would voluntarily release wasps in his or her yard. But most wasps pose no threat to people or pets. Many wasps are so small that even if they did sting you, you'd never notice. But to a caterpillar, these wasps are serious threats. Some eat the 'pillars outright. Others lay eggs on the caterpillar's body. When the eggs hatch, the wasp larvae eat tunnels through the caterpillar's body, then emerge as adults and fly off to find new caterpillars. (The process is fatal to the caterpillar.) If you find caterpillars in your garden with little white or yellow eggs on their backs, leave them alone: Those are wasp eggs.

With a little time and a little practice, you can put these beneficial insects to work protecting your crops, and your garden will be less toxic as a result.