The tender leaves of a wide variety of tree species are food for fall and spring cankerworms, leaf-chewing caterpillars. Elm, oak and apple are favorites; however, cankerworms attack many other hardwoods including:
What are the symptoms of a cankerworm infestion?
Chewed and ragged leaves are unsightly as damage occurs suddenly in late April through mid-May. However, most concerning is the stress brought on by leaf loss at a time when leaves are essential for nutrients for tree growth.
Watch your trees for:
- Holes in and along the margins of leaves
- Skeletonization of leaves (early damage)
- Total loss of foliage (advanced damage)
- 1- to 1 1/2-inch long caterpillars with legs in the front and rear
What do cankerworms look like?
Caterpillars vary in color from green to black. When full-grown, they are approximately one inch long. Because of their small size, the pests are easily blown from tree to tree and property to property.
Treatment and Management Options
Cankerworm populations can be reduced so that less feeding occurs, thereby helping to protect the health of your trees. Prevention is key! Tree banding is an option available in late fall to trap and control cankerworms on your trees. For trees affected by cankerworm during spring, a pesticide treatment is recommended to help control worms.