Hosts: Sugar, red and mountain maples, oak, elm, beech, quaking aspen, and willow
Evidence: Look for tattered leaves that are webbed (nested) together in a clump. Within the leaves you may find mottled and striped larvae, varying in color from pale yellow to greenish or brown (a), brown and skeletonized leaves, and frass.
Life Cycle: There is one generation per year. Winter is spent as a prepupa in a cocoon in the duff. Moths emerge in the spring to lay eggs on leaves that are already partially rolled by other insects. Young larvae feed as skeletonizers on these leaves, while older larvae web groups of leaves together as they feed.
Management: Trees that are more exposed, such as those in urban settings and portions of the crown that are more open tend to have heavier infestations. Many parasites and predators have been found associated with the maple webworm and are thought to be significant control agents. Chemical control is not usually necessary.
Similar Species: Several species of Psilocorsis (Pyralidae) may also occur on the same hosts. These species web leaves together flat and cause tattering as they feed.
Figure a: Ronald S. Kelley, Vermont Department of Forests, Parks and Recreation, Morrisville, VT.
Drooz, A.T. 1985. Insects of Eastern Forests. USDA Forest Service Miscellaneous Publication 1426. p. 180;
Rose, A.H. and Lindquist, O.H. 1982. Insects of Eastern Hardwood Trees . Canadian Forest Service Publication, Forestry Technical Report 29. p 117-118.