common name: yellowstriped oakworm (suggested common name), Peigler's oakworm
scientific name: Anisota peigleri Riotte (Insecta: Lepidoptera: Saturniidae)

Introduction - Distribution - Description - Biology - Host Plants - Natural Enemies - Management - Selected References

Introduction

The yellowstriped oakworm, Anisota peigleri, is an occasional pest on oak trees in the southeastern United States. In Florida, outbreak populations defoliated laurel, water and Shumard oaks in Gainesville from 1996 until 2001. Even when defoliation is not severe, the falling frass (droppings) and large numbers of caterpillars are a major concern for many homeowners. Frass commonly stains driveways, walkways, pool decks and other outdoor structures.

Distribution

Anisota peigleri occurs in southeastern Kentucky, eastern Tennessee, western North Carolina, the Piedmont and coastal areas of South Carolina, northern Georgia, Alabama and north central Florida. Gainesville, Florida is the southern-most point at which it has been collected. The biologically similar orangestriped oakworm, Anisota senatoria (J. E. Smith), has a much larger range, occurring from Minnesota and Maine southward to Texas and Florida (Tuskes et al. 1996, Riotte & Peigler 1980, Serrano & Foltz 2003)

Description

Adults: The adult female is reddish-orange in color and about 3/4 to 1 inch (18 to 25 mm) in length. The forewing has a small white spot, a dark line, and numerous dark speckles. The hind wings are somewhat paler and have an indistinct line. Females are distinguished from males by their larger size, threadlike antennae, and the characteristic shape and coloration of the wings. Males are smaller than females, the body ranging from 5/8 to 3/4 of an inch (15 - 20 mm) in length. The forewings are dark reddish brown with a small white spot and a larger whitish translucent patch. The hindwings are mostly reddish brown. Males have plumose (featherlike) antennae that they use to locate females by tracking the pheromones females release during their "calling."

adult female

adult male

Eggs: Eggs are yellow to orange-yellow in color (black when parasitized), spherical in shape, and about 1 mm in diameter.

eggs on underside of oak leaf

Larvae: The first stage caterpillars are yellow with a black head and two prominent horns arising from the second thoracic segment. The second stage caterpillars retain the yellow to yellow-green color and are slightly larger. During the third and fourth stages the caterpillars change from the yellow to yellow-green color to a black color. Eventually, larvae become black-bodied with yellow stripes running along their sides. Fully-grown larvae may be 2 inches (50 mm) long. All have the black coloration with yellow stripes, prominent black horns arising from the second thoracic segment, and a row of small spines running along the body behind each of the horns.

young caterpillars skeletonizing an oak leaf

3rd and 4th stage caterpillars

mature oakworms

Pupae: Pupae, like adults, vary in size according to sex. Male pupae range from 3/4 to 1 inch (18 to 25 mm) and female pupae range from 1 to 1 1/4 inch (25 to 30 mm) in length.

pupa and cast larval skin

Biology

The yellowstriped oakworm has only one generation per year throughout its range. Here is the life cycle we have observed in northern Florida where it is generally about one month later than in northern Georgia and the western areas of the Carolinas. Moths begin appearing in mid August and are present into early September. Moths may be seen resting on shrubs, tree trunks, and the walls of buildings. Females, after mating, lay about 150 eggs (range 15 to 380). Egg clusters are generally located on the underside of oak leaves at the ends of the lowest branches. Spent females are sometimes found beside their eggs.

female resting after laying eggs

Hatch occurs in 1 to 1 1/2 weeks and then the small caterpillars move to an adjacent leaf to begin feeding as a group. These small larvae consume only the soft portions of the leaf, leaving behind the leaf skeleton. At this stage the caterpillars are most easily located by looking in the vicinity of skeletonized leaves. After several days of feeding and growing, the 1st stage caterpillars shed their head capsule and skin and become second stage larvae. Caterpillars continue to feed and stay in groups. Larger caterpillars consume entire leaves leaving branches with nothing but bare twigs. After five to six weeks, the mature caterpillars cease feeding and disperse down from trees to pupate. This is the time, about mid October in Florida, when most people notice and are likely to be bothered by the oakworms. Oakworms pupate about 2 to 3 inches deep in the soil, "overwintering" in this stage for nearly ten months. Moths emerge the next year to begin the cycle again.

Host Plants

Anisota peigleri feeds on various oaks in the red oak-black oak group. In Florida this oakworm feeds primarily on Shumard oak (Quercus shumardii) and water oak (Q, nigra). Other common hosts are laurel oak (Q. laurifolia) and southern red oak (Q. falcata). Live oak (Q. virginiensis) is a white oak and does not support larval development.

Natural Enemies

Oakworm populations are subject to the typical variety of parasites and predators that affect leaf- feeding insects. Primary parasitoids of A. peigleri are the Hymenopterans Hyposoter fugitivus (Say), Anastatus reduvii (Howard), and Aprostocetus sp. and the Dipterans Winthemia datanae (Townsend), Lespesia anisotae (Webber), and Gnadochaeta sp. Secondary parasitoids, all Hymenoptera, are Isdromas lycaenae (Howard), Gelis tenellus (Say), Perilampus hyalinus (Say), Ceratosmicra meteori Burks, and Brachymeria ovata (Say). Invertebrate predators include jumping spiders and vespid wasps. Vertebrate predators include birds that prey on caterpillars in the trees and moles, mice, and shrews that prey upon caterpillars and pupae on the ground. Also, various pathogens likely infect pupae in the soil.

Management

Oakworm populations occasionally reach levels that completely defoliate host trees. Most oaks can tolerate one such defoliation with little impact on their health. Repeated defoliations, however, will weaken the trees and lead to infestation by secondary insects and pathogens.

Here are some steps for promoting tree vigor and reducing yellowstriped oakworm populations:

Insect Management Guide for landscape plants

Selected References

Authors: David Serrano and John L. Foltz, University of Florida
Photographs: David Serrano, John L. Foltz, and P. M. Choate, University of Florida
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-335
Publication Date: October 2004
Copyright 2004 University of Florida

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