The Most Hardworking Bugs: Garden-Friendly Insects

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There are hundreds of species of beneficial insects that feed on garden pests. Meet a few of the most common ones.

Lady Beetles
• Family: Coccinellidae

Although scores of species of lady beetles (ladybugs) exist, the adults of all species are round or oval; many are brightly colored and spotted.

Females periodically lay masses of orange-yellow eggs that hatch in about five days. The larvae are elongated, usually dark in color, and flecked with orange or yellow. They can crawl rapidly over plants, searching for food. Lady beetles reproduce rapidly during the summer and can complete a generation in less than four weeks under favorable conditions. As a result, they often overtake a pest outbreak before it becomes a real problem.

The adults feed on aphids and other small, soft-bodied pests as well as insect eggs. In addition, adults feed on nectar and particularly pollen to sustain them when their prey are not available. The larvae feed on a great many insects, particularly aphids, scales, small beetle larvae, caterpillars, and insect eggs. Almost all species of lady beetles feed on insects and mites.

Unfortunately, lady beetles are slow to arrive in the spring and often leave the garden by late summer. To encourage them, try to tolerate a few pest insects, enough to provide for their ­increase, and plant a variety of nectar and pollen sources.

Syrphid Flies
• Family: Syrphidae

With their orange- or yellow-and-black color scheme, adult syrphid flies, also known as flower or hover flies, look remarkably like bees or yellowjacket wasps. Some even buzz. However, they are harmless, visiting flowers for the nutrients that pollen and nectar provide so that they may reproduce.

The larvae of syrphid flies are tapered, legless green or gray maggots that feed on aphids; they are particularly valuable in controlling aphid infestations early in the season when it’s still too cool for lady beetles and other predators. The maggots are ­particularly adept at working their way into curled leaves and other protected areas that other kinds of predators are unable to penetrate. Ants, which routinely drive off other predators that threaten the aphids that they are guarding for their honeydew, apparently don’t bother ­syrphid fly maggots, perhaps because the maggots often cover their bodies with aphid carcasses.

Adult syrphid flies are less picky than some other beneficial insects about the types of flowers they will visit. Although preferring small, shallow flowers such as sweet alyssum, they also often visit larger flowers, such as ­cosmos.­ Be aware that syrphid flies are particularly sensitive to most commonly used persistent synthetic insecticides.

Green Lacewings
• Family: Chrysopidae