Red Worms Are Eating My Apple Tree

Identification

• The redhumped caterpillar is among the pests that feed on apple trees. The pests are 1 to 1 ½ inches long and have yellow bases with red to black colored, longitudinal stripes on the body. The head and the humped fourth body segment are orange to brick red. The worms raise their hind ends when resting.

Damage

• The caterpillars infest and feed on foliage undersides, skeletonizing entire leaves. Older worms eat the whole leaf with smaller veins. Severe infestation can defoliate the tree. In case a light population, the leaves on few branches are damaged. The pests are more prevalent following a warm winter.

Control

• Use natural predators, such as like parasitic wasps, in infested trees. Prune and remove branches with heavy worm presence. Chemical control options include the use of Bacillus thuringiensis or spinosad. BT works best on younger caterpillars. If you delay use of insecticides, they usually prove ineffective.