Description
    The yellow-necked caterpillar is closely related to the walnut caterpillar. It feeds on black walnut as well as other forest trees throughout most of the eastern United States.

    Full-grown larvae of the yellow-necked caterpillar are about 2 inches long with a black body and black head. The "neck" area behind the head is characterized by a bright orange-yellow spot. The remainder of the body is marked with four longitudinal yellow stripes interspersed with black, and the entire body is clothed with long, soft, white hairs. The larvae are gregarious and feed in large colonies on leaves near the tips of twigs and branches.

Injury
    Occasional outbreaks of the yellow-necked caterpillar may completely defoliate black walnut trees.

Control
    When outbreaks occur, consult your local county extension agent for recommended chemical controls. Removing larvae by hand is also effective.