Description
The redhumped caterpillar (Schizura concinna) is so named because of the characteristic brick red hump on its back. This caterpillar also has a red head and red stripes along its body. It is a fairly large caterpillar, as much as 1½ inches long when fully grown, and has the unusual characteristic of resting with its hind end elevated. The redhumped caterpillar feeds on a wide variety of deciduous fruit, nut, and ornamental trees. Sweet gum, walnut, and plum are favorite hosts. The caterpillars feed in groups on the lower leaf surfaces when young. As they grow they tend to disperse and eat entirely through leaves, leaving only the largest leaf veins. Often, just one section of a tree will be defoliated, but occasionally a large population will defoliate the entire tree. This slows growth and may reduce fruit quality, but the tree will usually recover from the defoliation. When mature, the caterpillars form cocoons in plant litter on the ground. The emerging adults are grayish brown moths with a wingspan of 1 to 1 3/8 inches. They lay eggs in groups on the undersides of leaves. There are as many as 4 or 5 generations a year.
Control
Spray infested areas of trees with an insecticide containing acephate or carbaryl. Make sure your plant is listed on the product label. The biological insecticide Bacillus thuringiensis (Bt) can also be used. If caterpillars are no longer present, delay spraying until the next generation of caterpillars is seen. Branches containing caterpillars can also be cut off and destroyed while the caterpillars are young and grouped together.
