University of Maryland Extension

Caterpillars - Trees


Many caterpillars feed on the leaves of shade trees throughout the season. 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 (see above photo), yellow necked, mimosa webworm, greenstriped mapleworm (rosy maple moth), catalpa worm and orange striped oakworm 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 B.t. in June when the bags are small.


Early season caterpillars such as gypsy moth should be controlled when larvae are small and before damage becomes extensive. The 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.

Forest tent and Eastern tent caterpillarsyellownecked caterpillar

Forest tent caterpillar (above) and Eastern tent caterpillar (below)

Yellownecked caterpillar

Mimosa webworm on a leafgypsy moth caterpillar

Mimosa webworm

Gypsy moth caterpillar

rosy maple moth and eggs on a maple leaf

Polyphemus caterpillar

Rosy maple moth and eggs
(Larva is the green striped maple worm)

Polyphemus caterpillar

Catalpa sphinx caterpillar on a leaforangestriped oakworm

Catalpa sphinx caterpillar

Orangestriped oakworm

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