-- Outbreaks occur periodically on oaks and other hardwoods over wide
areas of the eastern half of North America. Growth loss and dieback
occur, but trees are seldom killed unless they sustain 3 or more successive
years of defoliation.
Insect (figure 6a). -- Caterpillars have pale bluish lines along
the sides of a brownish body; a row of keyhole-shaped white spots down
the middle of the black back; sparsely covered with whitish hairs; and
reach 2 inches (50 mm) at maturity. Adult moths are buff brown with
darker, oblique bands. Egg masses of 100 to 350 eggs encircle the twigs
and are covered with frothy, dark brown cement.
Injury (figure 6b). -- The first noticeable signs of attack are
sparse crowns and falling frass. Caterpillars often cluster on the lower
trunks of infested trees. Trees or even stands may be completely defoliated
-- Eggs hatch in early spring. Caterpillars feed for 4 to 6 weeks on
the opening buds, foliage, and flowers. Despite its name, this species
does not form tents. Pupation occurs in yellowish cocoons and lasts
10 to 14 days. Moths emerge from late May to July and deposit their
eggs, which overwinter. There is one generation per year.
-- Natural controls include insect parasites of the pest's eggs, larvae,
and pupae. Predators, virus and fungus diseases as well as high and
low temperatures also kill forest tent caterpillars. Several chemicals
and a microbial insecticide are registered for control.
6. -- (a) Forest tent caterpillar larvae; (b) defoliation by forest