The army worm is the larval stage of a moth in the cutworm family. It ranges through the Midwest and southern United States in the summer months. Army worms retreat to the Gulf Coast, Central America and the Caribbean in the winter. Army worms have been reported in coastal states, including Vermont and California. They are nocturnal pests that primarily feed on grasses. The army worm can be a problem for an apple tree as well other fruit trees, where it feeds on leaves and fruit. There are several means of killing army worms, including utilizing natural predators and pesticides.
Mow around the base of the apple trees to destroy the army worm's habitat.
Examine the leaves of the apple tree for signs of army worms. Hand-pick the worms from the tree and drop them into a bucket of soapy water.
Release one trichogramma wasp per square foot of orchard space. The wasps will feed on army worm eggs and reduce the population.
Put on protective clothing, including long-sleeved shirt, long pants, gloves, eye protection and breathing protection before working with pesticides.
Mix a pesticide specifically designed to kill army worms according to the instructions on the package.
Pour the pesticide into a spray applicator's holding tank. Close the lid and prime the applicator by grasping the pump handle and working it back and forth.
Grasp the applicator wand in one hand and the holding tank in the other. Gently squeeze the trigger on the wand to release the pesticide in a spray.
Pass the wand over the tree using even strokes to apply the pesticide to the tree.