Fall Webworm - Hyphantria cunea Drury

Adult moth, 1 inch, with eggs                      Mature caterpillars
H.C. Ellis, The University of Georgia,  www.ipmimages.org            Lacy L. Hyche, Auburn University, www.ipmimages.org 
                

Webbed tenting in tree                                   
H. C. Ellis, The University of Georgia, www.ipmimages.org


HOSTS: Apple, cottonwood and cherry are the most common hosts, but over 100 species of hardwood may be affected.

DESCRIPTION: The mature caterpillar is yellowish to tawny brown in color with a dark stripe down the back and rows of distinctive orange-yellow tubercles on each side. The body is covered with tufts of long, silky gray hairs. The adult moth is satiny white with long soft hair and may have brown or black spots on the wing. Wingspan is about 1-1¼ inches long.

LIFE CYCLE: The fall webworm overwinters as a pupa in a light colored cocoon on the ground or under bark. In late spring/early summer adults emerge and lay eggs. Females deposit eggs on leaves in masses of 300 to 400. Eggs hatch in about 10 days. They feed gregariously and spin lightly woven webbed tents which contain the leaves on which they feed. The webs expand as the larvae grow and can reach several feet in diameter by late summer. The larvae mature in the late summer/early fall when they wander from the host tree to search for a protected location to pupate.

CONTROLS: There are many insect and bird predators. Remove and destroy nests. Bt is effective on young, smaller larvae. See Bacillus thuringiensis.

Missoula County Extension Office; Missoula, Montana 59808 - Updated for 2006