Description
Caterpillars, the larvae of moths and butterflies, are serious pests of garden plants. Moths and butterflies do not feed on tissue or harm plants, but drink nectar from flowers. They may also help to pollinate flowers. Caterpillars are smooth, hairy, or spiny wormlike creatures with 3 pairs of legs near their heads and several pairs of prolegs (false legs) in the middle and rear of the abdomen. Their mouthparts are adapted for chewing plant tissue. They generally confine themselves to tissue that is soft and succulent. After hatching, caterpillars go through as many as 11 stages of development (instars). At the end of each instar, caterpillars must molt (shed their skin) to make room for their larger body size. During the first instars, caterpillars may feed as leafminers between the upper and lower surfaces of leaves; or as skeletonizers, eating only one leaf surface. As the caterpillars increase in size in later stages, they require more food, devouring entire leaves. Caterpillar populations often fluctuate greatly from year to year due to unfavorable environmental conditions and to control by natural enemies such as birds, rodents, diseases, and other insects.
Control
Inspect garden plants periodically for signs of caterpillar infestation. Control caterpillars on ornamentals with an insecticide containing acephate or carbaryl. Spray food crops with an insecticide containing diazinon, carbaryl, malathion, or the biological insecticide Bacillus thuringiensis (Bt). Make sure your plant is listed on the label.
