Eastern Tent Caterpillar (Malacosoma americanum)

Overview

• Eastern tent caterpillars are social insects known for building silk nests in trees.
• Commonly found in cherry, apple, and various other trees.
• Recognized more often by their nests than their appearance.

Appearance

• Inhabit silk tents in tree branches, particularly in the crotches of trees.
• Dark larvae with white stripes down their backs and brown/yellow broken lines on the sides.
• Blue oval spots are visible along their sides.
• Moths are drab with parallel cream lines on tan or reddish-brown wings.

Habitat and Distribution

• Found throughout the eastern United States, extending to the Rocky Mountains and southern Canada.
• Prefer sunlit areas and are rarely found in shaded woods.

Life Cycle

1. Egg
   • Female lays 200-300 eggs in late spring.
2. Larva
   • Develop in a few weeks but remain dormant until spring when leaves appear.
3. Pupa
   • Spin silken cocoons; pupal case is brown.
4. Adult
   • Moths emerge in May and June, living only to reproduce.

Feeding Habits

• Prefer cherry, apple, plum, peach, and hawthorn trees.
• Can cause defoliation if populations are high.
• Adult moths do not feed.

Special Adaptations and Defenses

• Communal living in silken tents helps maintain warmth in fluctuating spring temperatures.
• Caterpillars huddle for warmth and add silk to tents regularly.
• Use silk trails and pheromones for communication and food location.
• Bristles deter predators; caterpillars thrash to ward off threats.

Importance

• Often a concern for homeowners due to their presence on ornamental trees.
• Do not typically harm healthy plants.

Related Species

• Can be confused with gypsy moths and fall webworms.

Sources

• Texas A&M University and University of Kentucky Agriculture Department.
• Books: "The Tent Caterpillars" by T.D. Fitzgerald, "Insects: Their Natural History and Diversity" by Stephen A. Marshall.