Importance. -- This caterpillar is a defoliator of oaks and a few other hardwoods throughout the United States. Infestations have been most common in the Appalachian and Ozark Mountains and foothills. Damage is more severe to shade and ornamental trees than to forest stands.

Identifying the Insect (figure 5). -- The larva is yellowish and black striped, and moderately covered with fine, white hairs. The head is jet black; the segment behind the head is bright orange yellow -- hence its name, yellownecked caterpillar. Full grown larvae are about 2 inches (50 mm) long. When disturbed, the larvae lift their head and tail in a distinctive "U" shape.

Identifying the Injury. -- Newly hatched larvae skeletonize the leaf; older larvae devour all except the leaf stalk. Individual trees, or even stands, may be defoliated during summer and early fall.

Biology. -- Moths appear during June and July and deposit white eggs in masses of 50 to 100 on the undersides of the leaves. Larvae feed in groups, maturing in August and September. Mature larvae drop to the soil and pupate at depths of 2 to 4 inches (5 to 10 cm) where they spend the winter. There is one generation per year.

Control. -- Natural enemies generally keep infestations in check. Chemical controls are occasionally needed.

Figure 5. -- Yellownecked caterpillar larvae.