Variable Oakleaf Caterpillar (Heterocampa manteo)
Anonymous. 1989. Insects and Diseases of Trees in the South. USDA Forest Service. Protrotection Report R8-PR16. 98 pp.
This defoliator is common throughout eastern North America. It attacks a wide variety of hardwoods, including all species of oaks, but prefers the white oaks. Some infestations have covered millions of acres, retarding tree growth and reducing vigor. Outbreaks occur periodically and usually subside after 2 to 3 years, before serious tree mortality occurs.
Identifying the Insect
The larval color is variable, but is generally yellowish green, with a narrow white stripe down the center of the back, and one or two yellowish stripes on the sides. The head is amber, with one dark and one light band on each side of the head. Mature larvae may reach 1 1/2inches (37 mm) long. The adult moth is ashy gray, with three dark wavy lines across each forewing. The wingspan is approximately 1 1/2 inches (37 mm).
Identifying the Injury
Young larvae skeltonize the leaf, while older larvae devour the entire leaf except the leaf stalks and main veins. There are two periods of defoliation-early May to late June and mid-August to late September.
There are two generations in the South and one generation in the North. In the South, the larvae feed from early May until late June and pupate in the soil. Second generation larvae feed from midAugust until late September, then move to the ground to spin cocoons and over winter. Adult moths emerge from cocoons by early spring.
Insect parasites and predators destroy eggs, larvae, and pupae. Winter mortality also helps keep most infestations in check. Chemical control is occasionally needed to protect high value trees.