Hosts: Aspen, willows, cottonwoods, and mountain
Western tent caterpillar is an early season defoliator with feeding
damages typically occurring between May and June. Symptoms include
moderate to complete defoliation of trees; large silken tents on
branches; and presence of larvae in and around the tents. Trees
repeatedly defoliated will have sparse foliage, minor branch dieback,
and in some cases, tree mortality.
larvae are 4 to 5 cm long and vary widely in coloration. Their heads
are blue to black and body color patterns are mixtures of black,
orange, and blue. Larvae are usually quite hairy.
Biology: Larvae overwinter as first instars inside
egg masses glued around twigs. Larvae emerge from egg masses in
spring and construct silken tents on branches that are used for
shelter and molting during the daytime. At night, caterpillars feed
outside of the tents. As the larvae mature, they disperse and become
solitary feeders. Moths emerge from cocoons and glue egg masses
to live twigs that are less than 2 cm in diameter.
Heavy defoliation of aspen for a number of years will cause growth
loss and branch dieback. Some mortality may also occur during prolonged
outbreaks. Outbreaks, however, are generally short lived, generally
lasting 2 to 3 years.
Insects and Diseases: See fall
webworm and foliar diseases.
References: 3, 15,