Barbara J. Bromley, Mercer County Horticulturist 97

Of the 686,000 known species of insects, about 100,000 species are found in North America. Of these, about 10,000, or 10 %, are enemies. The rest, 90,000, are either harmless or beneficial. The following insects are parasites or predators of pests.


antlion and larvaefeeding habits: Larvae trap ants and other small insects.

description: Adult resembles a dragonfly and is 1 l/2″ long, dark brown with long membranous wings and clubbed antennae. Larvae, called doodlebugs, are brown or gray and have a plump abdomen and narrow thorax. They dig holes in sand to trap their prey, then scuttle backwards.

notes: Eggs and larvae overwinter in sand. Up to a 2-year life cycle. One generation per year.


assassin bugfeeding habits: Adults and nymphs eat flies, caterpillars, aphids, Colorado potato beetles, Japanese beetles, leafhoppers, Mexican bean beetles, bees, butterflies.

description: l/2″ long, black or brown, large eyes in narrow head, large front legs armed with spines for grabbing prey. Stout beak. Nymph may be brightly colored.

notes: Can inflict a painful bite. Overwinter as adults, nymphs, or eggs. The giant wheel bug is a predator on Japanese beetles and pine sawflies. To attract assassin bugs, provide shelter in permanent plantings.


big eyed bugfeeding habits: Aphids, small caterpillars, leafhoppers, tarnished plant bug, chinch bugs, spider mites, insect eggs.

description: l/4″ long, grayish to tan, huge black eyes, tiny black spots on head and thorax. notes: Hibernates in garden trash for winter; likes alfalfa, carrot family plants, pigweed, and goldenrod.


brown lacewingfeeding habits: Aphids, mites, thrips, scale insects, and leafhopper nymphs. Adults eat aphids and mealybugs.

description: Adults are small and fragile with lacy wings.

notes: larvae are called aphid wolves. Oval eggs are stuck to the surface of leaves and bark of trees.


damsel bugfeeding habits: Aphids, leafhoppers, treehoppers, psyllids, plant bugs, mites, small caterpillars, redheaded pine sawflies

description: Are flat, gray or brown, l/4″ long with body narrowed toward head. Large front legs.

notes: Favors low growing plants, especially alfalfa.


damsel flyfeeding habits: Aphids, leafhoppers, treehoppers, caterpillars, many immature insects, mosquitoes, midges.

description: 3/8″ long, small slender body.

notes: Attracted to wildflowers.


Lightningbugfeeding habits: Larvae eat slugs, mites, and small crawling insects. Adult not as efficient a predator.

description: Adult 1/2″ long, flat, brown to black, “light apparatus” on underside. Larvae are called glowworms and look like flat beetles with jaws. .

notes: Larvae hunt at night. Prefers moist areas shaded by vegetation to lay eggs.


green lacewing and larvaefeeding habits: Larvae eat aphids, mealybugs, mites, scale insects, whiteflies, and eggs of caterpillars, mites, thrips. Eat up to 60 aphids per hour.

description: Adults 1/2″ to 3/4″ long, slender body, delicate long green wings. They lay oval eggs on slender stalks which hatch in 6-14 days. Larvae are called aphid lions and are 3/8″ long, yellowish-gray with brown marks and tufts of hair. Have long thin jaws which curve like ice tongs. In 2-3 weeks from hatch, they spin whitish pea-sized cocoons on a leaf.

notes: Overwinter in cocoons in pupal stage. 3-4 generations per year. Are attracted to weeds such as goldenrod, dandelions, yarrow, wild carrot and pollen and nectar producing flowers. To encourage lacewings, provide water during dry periods.


ground beetlefeeding habits: Common ground beetles are a fierce predator of slugs and snails. Fiery searchers, a type of ground beetle, eat caterpillars, grubs of scarab beetles, slugs, eggs and larvae of ants, aphids, Colorado potato beetles, cabbage maggots, flea. beetles, gypsy moths, nematodes, spider mites, thrips, armyworms, tent caterpillars.

description: 1″ long, black to purplish, hard shells, long legs. Larvae whitish to light brown, elongated with large heads.

notes: Adults, called caterpillar hunters, overwinter in garden trash. The fiery searcher overwinters in soil. There are many species. Are attracted to clover, camphorweed, pigweed, low plants, and logs.


lady beetles and larvaefeeding habits: Larvae and adults eat aphids, thrips, mealybugs, various small larvae, beetle grubs, scales, spider mites, whiteflies, other soft-bodied pests, and insect eggs. Favorite food depends on ladybird beetle species.

description: larvae are 1/4″to l/2″ long, covered with tiny spines, gray or black with blue and orange markings, and resemble tiny alligators. Full grown in 20 days. Eggs are yellow-orange and spindle-shaped. Adults of the common lady beetle are l/4″ long, reddish-orange beetles with spots (usually 12) and generally feed on aphids. Other species may be solid black, gray, or yellow. Darker beetles with two or more spots generally feed on other pests such as scales, whiteflies,. and mites.

notes: Are attracted to pollen and nectar plants such as yarrow, evergreen euonymus, alfalfa, morning glory, tansy, goldenrod. One generation per year. Adults over-winter in garden litter.


Minute Pirate Bugfeeding habits: Small caterpillars, leafhopper nymphs, scale insects, thrips, and other small insect pests and eggs.

description: Adults are black and white and smaller than l/8″. May be found in corn silk or stinging nettle. Insidious flower bugs are l/16″ and black.

notes: Insidious flower bugs are an important enemy of thrips. Grow goldenrod, yarrow, and other pollen plants.


Plant wildflowers, especially from the daisy and carrot families, to encourage them to remain in yard.

BRACONIDS:braconid waspfeeding habits: Aphids, armyworms, beetle larvae, tomato hornworms, importe cabbageworms, European corn borers, European pine shoot moths, cutworms, . gypsy moths, tent caterpillars, codling moths, oriental fruit moths, flies.

description: Adults range from l/l6″ to 5/8″ long and are black, yellowish, or red. Larvae are white and wormlike. Light brown or whitish cocoons may be seen on the backs of hornworms and other caterpillars. NY.

notes: Prefers high humidity and temperatures above 59°F. To attract braconids grow nectar producing plants with small flowers. They leave a round exit hole in back of victims. Usually overwinter as larvae or pupae.


chalcid waspfeeding habits: Aphids, asparagus beetles, leafhoppers, cankerworms, seal insects, whiteflies, various caterpillars and beetles.

description: Adults l/l6″ to 3/8″ long. Feed on honeydew and plant exudates.

notes: Adults feed on some hosts, lay eggs on or in others. Are seriously affected by sulfur, miticides, road dust, chlorinated hydrocarbons.


ichneumid waspfeeding habits: Eastern tent caterpillars, cutworms, fall webworms, sawfly larvae, European corn borers, and other larvae.

description l/8″ to 3″ long, typically slender with a long abdomen and a long threadlike ovipositor.

notes: Lay eggs in hosts. Plant pollen and nectar producing flowers to attract them.


trichogramma waspfeeding habits: Aphids, armyworms, cankerworms, loopers, fall webworms, leaf rollers, gypsy moths, mealybugs, scale, whiteflies, homworms and various beetles larvae.

description: Minute.

notes: Parasitize eggs of host. These eggs turn black.



praying mantisfeeding habits: Eat all insects, both damaging and beneficial, including brothers and sisters. )

description: To 6″ long, green or brown, assume a praying posture. Egg mass looks like a 1″ mass of light brown foam wrapped around a twig.

notes: Single female lays 3-6 masses containing 50-400 eggs. Mass enclosed in a sticky substance which dries to form a protective covering for the eggs. Not reliable as a control for pest species.


robber flyfeeding habits: Captures flying insects such as bees, bugs, beetles, flies, grasshoppers, leafhoppers, wasps, butterflies, and moths. larvae eat grasshopper eggs, white grubs and beetle pupae.

description: l/4″ to 3/4″ long, gray with long legs, stout beak and a hairy mouth. Produce loud buzzing sounds.

notes: Over-winter as white, flat cylindrical larvae in the soil. One generation per year.


rove beetlefeeding habits: Mites, bark beetle larvae, aphids, small worms, slugs, fly eggs, nematodes, springtails.

description: l/8″ to 1 l/4″ long, slender bodies, short wing covers, resemble earwigs without pincers. Red spider destroyers are small hairy black beetles with yellow larvae (eat 20 mite larvae per day).

notes: Attracted to decaying plant and animal material, compost. Maintain permanent plantings for their protection.


soldier beetlefeeding habits: Adults feed on aphids, beetle larvae and caterpillars, grasshopper eggs, cucumber beetles, spider mites.

description: Adults are 1/2″, long, golden or dull orange, black markings on white thorax and head. Leathery, rather than hard, wing covers. Resemble lightning bugs, but do not light up.

notes: Also called Pennsylvania leather wing. Overwinter as mature larvae in garden trash or soil. Are lured to wild lettuce, milkweed, hydrangea, goldenrod, and pollen rich plants. Maintain permanent plantings.


spined soldier bugfeeding habits: Fall armyworm, caterpillars, sawfly larvae, bean beetle larvae.

description: Resemble stinkbugs, but have sharp points on the “shoulders” of the thorax. notes: Maintain permanent perennial gardens for their protection.

SYRPHID FLIES (also Hover flies, Flower flies):

syrphid flyfeeding habits: Mainly aphids, but also leafhoppers, scale, mealybugs, thrips.

description: Adults are l/2″ long, black with yellow bands, with short antennae, on pair of wings. They hover and darts like hummingbirds and feed on nectar. Larvae are legless, tan or green small slug-like maggots on flowers.

notes: Attracted by coreopsis, baby blue eyes (Nemophila), candytuft, morning glory, and other nectar flowers. Several generations per year. Hibernate as pupae.


tachnid flyfeeding habits: internal parasites of adults and larvae of beetles, grasshoppers, squash bugs, caterpillars (including gypsy moth, cutworms, armyworm, and browntail), sawflies, and other insects.

description: Adults are gray or brown with pale markings, look like houseflies, but are larger (nearly 1/2″ long), drab and bristly. Larvae are grayish to greenish white, spined maggots.

notes: Feed on nectar and plant exudates. Larvae hibernate in the body of the host. To encourage their spread, don’t kill a caterpillar with white eggs stuck to its body.


tiger beetlefeeding habits: Ants, aphids, beetles, grasshoppers, caterpillars, and other crawling insects. larvae feed on small insects.

description: Adults are 3/8″ to 7/8″ long, metallic green, blue, purple to black, and bronze. Big eyes, long antennae, long thin legs. Larvae are white, yellow, or dusky.

notes: Adults trap their food. Overwinter as a larvae or adults. Don’t use light traps or leave outdoor lights on all night, because they are attracted to lights.


waspfeeding habits: Small insects which they catch to feed their young.

description: Yellow jackets: black and yellow, l/2″ to 3/4″ long. Eggs are laid papery cell colonies in hollow areas or in the ground. Adults feed on nectar an pollen.

Others include German and bald faced hornets, Polistes or paper wasps, mud daubers, cicada killers, and Scoliids or digger wasps.

Other insects, such as honeybees and bumble bees are beneficial as efficient pollinators. Yellow jackets are pollinators and feed small insects to their young.

Members of the carrot family (Umbelliferae) include dill, caraway, lovage, fennel and parsley. Mint family (Labiatae) includes catnip and lemon balm as nectar plants. Daisy family (Compositae) includes coneflower, yarrow, and daisy as pollen and nectar sources.