Beneficial Insects for Your Garden’s

Adapted from “Natural Enemies are Your Allies” by the University of California.
Photos courtesy Regents of the University of California

Remember the three “P’s” of beneficial insects: pollinators, predators and parasites.
Pollinators, such as honeybees, fertilize flowers, which increases the productivity of food crops ranging from apples to zucchini.
Predators, such as lady beetles and soldier bugs, consume pest insects as food.
Parasites use pests as nurseries for their young. On any given day, all three “P’s” are feeding on pests or on flower pollen and nectar in a diversified garden.
If you recognize these good bugs, it’s easier to appreciate their work and understand why it’s best not to use broad-spectrum herbicides. Here are 10 worth knowing:

Aphid mummies are the bodies of aphids that have been killed by parasites such as mini wasps. The hole was made when an adult mini wasp emerged from the aphid. You can tell if beneficial mini wasps are present by looking closely for the mummies in aphid colonies. To allow the mini wasps to thrive, avoid spraying pesticides.	Ground beetles (Coleoptera) are large, often black, shiny beetles that frequently are encountered beneath mulch. About 2,500 species are native to North America. Ground beetles are most active at night. They consume soil-dwelling, soft-bodied pests, including slugs, snails and caterpillars. Although they are called ground beetles, some species do climb trees to feed on caterpillars. Ground beetles need a stable habitat because they do not move around very much. They also grow more slowly than many other insects; a complete life cycle, from egg to larvae to pupae to adult, takes one year, and most adults live two to three years.

Lacewings (Neuroptera) may be brown or green, and adults are usually one-half to three-fourths-inch long, with delicate, transparent wings. Eggs are often seen stuck to leaves on short threads. The larvae, known as aphid lions and aphid wolves, feed on aphids, mealybugs, scale, thrips, mites, and other larvae and eggs. The predacious period lasts 15 to 20 days, during which a larva will eat 100 or more insects a day. Adults need pollen, nectar and honeydew (secreted by aphids and other sucking insects), as well as water.
	Lady beetles (Coleoptera) are yellow-orange to red, with black spots. Adults are one-fourth-inch long. Both adults and larvae, which look like tiny blue-black and orange alligators, feed on aphids, scale, thrips, whiteflies, spider mites, mealybugs and other soft-bodied pests. Adults are attracted to nectar and pollen plants. Lady beetles overwinter as adults in leaf litter, tree crevices and homes.
Minute pirate bugs (Orius tristicolor ) attack mites and any tiny insects, especially thrips.
	Parasitic flies include more than 1,300 species of tachinid fly (Diptera), which look like hairy houseflies. They lay their eggs on a number of caterpillars, including corn earworms, cabbageworms, cutworms and many other garden pests. Closely related humpback flies parasitize ants, bees, beetles and scale insects.
(Hemiptera) include soldier bugs, which look like squash bugs but have sharp spines on their shoulders, and big-eyed bugs (above), which have large bulging eyes on the sides of their heads and no shoulder spines. Both types of predators eat leaf beetle larvae, small caterpillars and many other insects. A third type of predatory bug, the one-fourth-inch-long, black-and-white minute pirate bug, feeds on thrips, mites and insect eggs. Adults of all three species overwinter in perennial weeds or other debris.
	Spiders (Arachnida) have eight legs rather than six, and they probably are the most abundant predators in home landscapes. The 3,000 species found in North America include web spiders, jumping spiders, crab spiders and many others. Spiders are general feeders that help keep many other insects in check.
Hover flies or syrphid flies (Diptera) are brightly colored flies that resemble bees and that hover and dart like hummingbirds. They don’t sting. The larvae, cylinder-shaped maggots with tapered heads, feed on aphids, mealybugs and other small insects. A larva may consume 400 aphids before pupating. Adults feed on pollen and flower nectar. Hover flies overwinter as pupae in the soil.
	Wasps (Hymenoptera) include numerous species of predators and parasites. Large paper wasps are predators, but many parasitic species such as braconids look like tiny flying ants. Some “micro-wasps” that parasitize eggs are so small you may never see them. Braconids lay eggs in the bodies of other insects, including caterpillars, tomato hornworms, aphids, thrips, Mexican bean beetle larvae and various borers. The eggs hatch and the larvae feed on their hosts’ body fluids. Braconids and other parasitic wasps are most active in warm weather, and they like humid conditions. They are attracted by nectar in small flowers.