Pest Control Library: Ladybugs
Adult ladybugs, or ladybird beetles, are typically a brick red or orange with black markings. But some are black, often with red markings. Their larvae look like miniature alligators, and they live up to their appearance by being voracious predators of many garden pests. That's why ladybugs are among the most visible and best known beneficial predatory insects.
There are more than 450 species of ladybugs in North America. Some are native and some have been introduced from other countries. Most North American species are beneficial, with both adults and larvae feeding primarily on aphids. They also feed on mites, small insects, and insect eggs. (There are two pest species in the group: the Mexican bean beetle and the squash beetle. Both adults and larvae of those species feed on plants.)
Most ladybugs found in gardens are aphid predators. Some species prefer only certain aphids while others will seek out and dine on most any kind of aphid. Some prefer mite or scale species. If aphids are scarce, they'll feed on the eggs of moths, beetles, mites, thrips, and other small insects, as well as pollen and nectar. Not as delicate and refined as they seem, they'll also feed on their own young.
Because of their ability to survive on other prey when aphids are in short supply, ladybugs are particularly valuable natural enemies of pests.
Ladybugs overwinter as adults, often in aggregations along hedgerows, beneath leaf litter, under rocks and bark, and in other protected places, including buildings. In spring, the adults disperse in search of prey and suitable egg laying sites. This dispersal trait, especially strong in migratory species such as the commercially available convergent lady beetle, affects the reliability of released adult beetles.
To encourage these beneficial insects into your garden, supply them with food and moisture. Small and shallow-faced flowers provide adults easy access to nectar and pollen: Plant alyssum, herbs from the dill and mint families, and flowers from the daisy family.
Photography by Georgy Csoka, Hungary Forest Research Institute, Bugwood.org