Spiny elm caterpillar

Nymphalis antiopa

23 host plants

Last updated March 14, 2026

Data Maturity Baseline

This profile contains verified pest data from extension databases. Regional field notes and expert review are in progress.

Purplish-black caterpillars with white specks, orange to red spots along the back, and long forked spines reach about 2 inches when mature on elm, willow, hackberry, and cottonwood. These spiny caterpillars feed in large groups and eat all leaves on a branch before moving; their presence is signified by defoliation of entire branches.

Well-established trees tolerate defoliation without serious injury. These caterpillars rarely warrant control measures. Prune defoliated branches if important for appearance. Spines do not cause serious human health impacts. Natural parasitic wasps usually maintain low populations.

Quick Reference

Order

Lepidoptera

Type

defoliator

Host Plants

Cultural Controls

Hand-pick caterpillars when practical.
Numerous parasites and predators, including parasitic wasps and some birds, help keep spiny elm caterpillar populations in check.

Host Plants (23)

Cephalanthus occidentalis Buttonbush, Honey Bells, Button Willow Globe Flower Chilopsis linearis Desert Willow, Flowering Willow, Catalpa Willow Quercus phellos Willow, Oak Rhus lancea African Sumac, Willow, Rhus Karee Salix alba Salix alba Salix babylonica Weeping Willow Salix caprea Salix caprea Salix integra Salix integra Salix magnifica Magnolia-leaf Willow, Magnificent Willow Salix matsudana Salix matsudana Salix pentandra Laurel, Willow, Bay Willow Salix phlebophylla Skeletonleaf Willow Salix purpurea Purpleosier Alaska Blue Willow Salix scouleriana Scouler's Willow Searsia lancea African Sumac, Willow, Rhus, Keree Ulmus americana American Elm Ulmus davidiana David Elm Ulmus davidiana var. davidiana unknown Ulmus davidiana var. japonica Japanese Elm Ulmus glabra Ulmus glabra Ulmus hollandica Dutch Elm, Holland Elm, Hybrid Elm Ulmus parvifolia Lacebark Elm, Chinese Elm Ulmus pumila Siberian Elm