These suspended larvae are a nuisance when the tree is located over a sidewalk or lawn area. The pupal stage occurs inside a small, 3mm long, white cocoon which is longitudinally ribbed. The pupa is black and when the moths have emerged it may be seen protruding from the empty cocoons. Small white patches of silk are often seen on the leaves where these insects are present - they spin and then use these silken pads as a protective cover under which to molt. As a result of the feeding of the larvae, the leaves are reduced to their upper surface only, often becoming almost trans- lucent and eventually drying out.
Outbreaks occasionally occur causing damage over large areas.
Several successive defoliations result in a reduction of growth, and sometimes part of the crown is killed. The larvae hatch, and at first begin feeding by tunneling in the leaves causing blotch or serpentine mines, but from the third instar on, they feed externally on the lower leaf surface. As a result of this later feeding, leaves appear skeletonized. Depending on population numbers, damage may be slight or even go unnoticed, except in outbreak years. In most of the northeast there are two generations of this insect a year.