University of Maryland Extension

Caterpillars - Trees

closeup of red humped caterpillar
Red humped caterpillar
Photo: Clemson University - USDA Cooperative Extension Slide Series , Bugwood.org

  • Many caterpillars feed on the leaves of shade trees throughout the season. Most do not cause significant damage.
  • Gypsy moth is an early season caterpillar that should be controlled on oaks.
  • Other early season caterpillars include Eastern tent caterpillar and cankerworms.
  • Mid-to-late season caterpillars such as bagworm, fall webworm, red humped, yellow necked, mimosa webworm, greenstriped mapleworm (rosy maple moth), catalpa worm, and orange striped oakworm caterpillars generally do not require control except on young trees or if heavy defoliation is occurring.
  • Bagworms should be controlled on evergreens. Pick off and destroy the bags during the winter. If needed, spray affected trees with Bt (Bacillus thuringiensis) in June into early July when the bags are small.

Management

  • Early season caterpillars such as gypsy moth should be controlled when larvae are small and before damage becomes extensive. T
  • he biological insecticide Bacillus thuringiensis (Bt) is effective on small caterpillars.
  • Hand picking of caterpillars can give adequate control of small populations on young trees.
  • Large caterpillars are difficult to control and may require a residual insecticide spray if populations are causing significant damage.
  • Control may be difficult on large trees unless spray coverage is thorough. Contact a certified arborist for spraying large, mature trees. 

Forest tent and Eastern tent caterpillarsyellownecked caterpillar
Forest tent caterpillar (top)               Yellownecked caterpillar
Eastern tent caterpillar 

Mimosa webworm on a leafgypsy moth caterpillar
Mimosa webworm                             Gypsy moth caterpillar

rosy maple moth and eggs on a maple leafPolyphemus caterpillar
Rosy maple moth and eggs                                  Polyphemus caterpillar

(Larva is the green striped maple worm)

Catalpa sphinx caterpillar on a leaforangestriped oakworm
Catalpa sphinx caterpillar                  Orangestriped oakworm

Rev. 2020

Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2020. Web Accessibility

University programs, activities, and facilities are available to all without regard to race, color, sex, gender identity or expression, sexual orientation, marital status, age, national origin, political affiliation, physical or mental disability, religion, protected veteran status, genetic information, personal appearance, or any other legally protected class. If you need a reasonable accommodation to participate in any event or activity, please contact your local University of Maryland Extension Office.