Hyphantria cunea (Arctiidae)

the fall webworm


Hyphantria cunea, the fall webworm, adult moth. Adults are white moths, occasionally having a few black spots or orange markings on body and legs.


Hyphantria cunea larva (caterpillar). Two distinct races are distinguishable at the larval stage. In the northern part of the insects' range, larvae have a black head capsule, a yellowish or greenish body with a dark stripe down the back and long whitish hairs that arise from black and orange tubercles located along its sides. In the south, larvae have an orange or reddish head, a yellowish-tan body with orange to reddish tubercles and brownish hair.


Webbing surrounding feeding area produced by Hyphantria cunea larvae. Larvae feed gregariously, forming large webs on tree branches. Immature larvae feed on the epidermis of both sides of the leaf, leaving the veins untouched. Mature larvae consume the entire leaf, leaving only the petiole.

Principal Hosts:

Approximately 120 deciduous species are host to the fall webworm, including alder, willow, birch, choke-cherry and cottonwood.

Economic Importance:

This pest is of minor importance in forestry, however, control on ornamentals is often required for aesthetic reasons.

References and Links:

FC: 219.

See HForest and JP17.

Additional Images:

Mature caterpillar with spines and dark spots. Webbing around branch produced by Hyphantrea cunea feeding. Young larvae on 'nest'. Older Hyphantrea cunea nest; note its messy appearance.
Fall webworm colony. Older nest.