The fall cankerworm is widespread in the northern part of the United
States, ranging south through the Appalachian Mountains to North
Carolina. Larvae defoliate many species of hardwoods, but in the South
seem to prefer oaks, hickories, and ash.
[Illustration: Mature fall cankerworm larva.]
The winged male and wingless female adults emerge on mild days in
November and December and mate. Females lay 6-300 eggs in neatly
arranged masses encircling small branches and twigs. The pale green
larvae hatch in late April or early May. As they mature they may remain
light green, or change to a very dark brownish-green depending on the
host. Newly hatched inch-worms (larvae) of the fall cankerworm chew
small holes in expanding leaves of their hosts, or may completely
skeletonize the leaves. Mature larvae consume all but the mid-rib and
major veins of the leaf. Feeding is usually completed in four to five
weeks, at which time larvae drop to the ground to pupate in the soil.
Cold, wet weather during the early larval period, and parasitization,
are responsible for sudden declines in established populations. Chemical
control has also been effective. A small wasp, _Telenomus alsophilae_
Viereck, has caused a sharp decline in outbreaks of cankerworm
populations. Usually, however, outbreak conditions must exist for
several years before the parasite can attain the density needed to cause
a decline.
[Illustration: Female cankerworm adult depositing eggs.]