Penn State Extension


Yellownecked Caterpillar

Datana ministra (Drury)

The yellownecked caterpillar is a key pest of shade trees. It is widely distributed throughout most of the eastern United States. Generally, it feeds on basswood, paper and yellow birches, elm, honeylocust, oak, maple, mountain-ash, and walnut. This insect is also destructive on the foliage of blueberry, apple, and other fruit trees.


The adult is a reddish brown moth. The front wings are cinnamon brown and marked with irregular fine dark lines. Adults have a wingspread of about 50 mm. The larvae are black with four yellow stripes on each side (Fig. 1). Their bodies are covered with long fine whitish hairs. The head is jet black; the segment behind the head is bright yellow, hence its name. Mature larvae are about 50 mm long. When disturbed, larvae assume a threatening posture. Usually, they lift both the head and posterior tip of their bodies, making a distinctive “U” shape.

Yellownecked cterpillars hanging from a stem in a c-shape.

Figure 1: Yellownecked caterpillars

Life History

Adults appear during June and July. Male moths may be attracted to lights. Females lay their white eggs in masses on the lower surface of leaves. Egg masses consist of 100 or more eggs. After hatching, young larvae congregate on foliage and feed in groups. During August and September mature larvae descend to the ground and burrow two to four inches into the soil where they overwinter as pupae. There is one generation per year.


Larvae congregate near the ends of twigs and branches. Newly hatched larvae skeletonize the foliage. Defoliation first appears on the periphery of the tree crown. Mature larvae consume all the tissues of infested leaves, except the larger veins. Ornamental, shade, and fruit trees are seriously defoliated. Damage is seldom of importance to trees in a forest.


There are several natural enemies that attack this pest. Birds such as robins feed on larvae. Predaceous bugs and parasitic flies may also attack this species. Monitor trees from mid-June through July for signs of this pest. Where possible remove foliage that contain white masses of eggs on the lower surface. If necessary, apply a registered formulation of an insecticide when larvae are small.


Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.

Authored by: Gregory A. Hoover, Sr. Extension Associate

Revised July 2013

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