Each harmful insect has a predator or parasite that attacks it, called a beneficial insect. Whether you know it or not, you rely on these allies to help keep the insect balance from tipping too far in the destructive direction. If you familiarize yourself with these good guys, you can encourage their presence in the garden and avoid killing these innocent bystanders.
Beneficial nematodes: These tiny, worm-like creatures live in the soil and prey on Japanese beetle grubs, as well as on army worms, cutworms, onion maggots, raspberry cane borers, and sod web worms.
Big-eyed bug: These fast-moving, 1/8- to 1/4-inch bugs resemble the pesky tarnished plant bugs, which are a favorite food of the big-eyes. They also dine on aphids, leafhoppers, spider mites, and some small caterpillars.
Braconid wasps: Several species of braconid wasps parasitize pest insects. Both the slender adults and tiny, cream-colored grubs feed on a range of pests, including aphids, cabbageworms, codling moths, and corn borers.
Centipedes: Indoors and out, multilegged centipedes feed on many insect pests. Most species don’t bother humans (unless you count the screech with which they’re frequently greeted), and none are dangerous.
Damsel bugs: These slender, 3/8- to 1/2-inch bugs have strong-looking front legs, and they prey upon aphids, caterpillars, leafhoppers, and thrips.
Ground beetles: Many beetle species live in or on the soil where both their larval and adult stages capture and eat harmful insects. They vary in color — black, green, bronze — and in size. Most live close to the ground, feeding on aphids, caterpillars, fruit flies, mites, and slugs, but the 1-inch-long caterpillar hunter climbs trees to feed on gypsy moths and other tree-dwelling caterpillars. Ground beetles bear an unfortunate likeness to cockroaches, but the latter have longer antennae and a different overall shape. Most of the helpful ground beetles are large, dark, and fast moving. They often have nasty-looking mandibles and eyes on or near the fronts of their heads.
Hover flies: The adults, resembling yellow jackets, are important pollinators, while the brownish or greenish caterpillar-like larvae have an appetite for aphids, beetles, caterpillars, sawflies, and thrips.
Ichneumonid wasps: A valuable ally in controlling many caterpillars and other destructive larvae, the dark-colored adult wasps (see the image below) vary in size from less than 1 inch to 11/2 inches. They have long antennae and long egg-laying appendages — called ovipositors — that are easy to mistake for stingers. The adults need a steady source of nectar-bearing flowers to survive.
Icheumonid wasps look threatening, but only spell danger for caterpillars and grubs.
Lacewings: These 1/2- to 3/4-inch insects have delicate green or brown bodies and transparent wings. The spindle-shaped, alligator-like, yellowish or brownish larvae feed on a wide variety of soft-bodied pests, such as aphids, scale, thrips, caterpillars, and spider mites. The distinctive, pale green oval eggs each sit at the end of its own long, thin stalk on the undersides of leaves.
Lady beetles (lady bugs): Both adults and larvae prey on soft-bodied pests, including mealybugs and spider mites.
Minute pirate bug: These bugs have a voracious appetite for soft-bodied insects, such as thrips, corn earworms, aphids, and spider mites. The adults are 1/4-inch long, somewhat oval-shaped, and black with white wing patches. The fast-moving, immature nymphs are yellow-orange to brown in color and teardrop-shaped.
Rove beetles: These beetles, which resemble earwigs without pincers, feed on soil-dwelling insects, such as root maggot eggs, larvae, and pupae. ....read more
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