Full-grown polyphemus moth caterpillars are nearly 3 inches long and are bright green with a brown head. On each angular body segment are six yellow-orange tubercles with small bristles. On most abdominal segments a yellow line runs through the brown spiracle and connects the first and second tubercles found on each side of the body. Common host plants include hickory, maple, hazelnut, oak, ash, walnut, sycamore, butternut, willow, elm, hawthorn, basswood and birch.

About the family

Royal moths and silkworm moths of the Saturniidae family include many of the largest and most colorful moths in North America and the world. These large caterpillar species are usually not considered pests. Although a single individual can consume relatively large amounts of foliage, their numbers rarely reach levels that would warrant control. But there are a few species that can do significant damage to many forest tree species. Upon completing their larval development, most saturniid caterpillars will pupate in large, tough silken cocoons usually attached to twigs or leaves or found on the ground. Many species have only one generation per year.

IPM1019, new February 2003