Yellowstriped Oakworm

Yellowstriped Oakworm in Gainesville, Florida

Anisota peigleri (Lepidoptera: Saturniidae)



Outbreak populations of a yellowstriped oakworm, Anisota peigleri, defoliated laurel, water and Shumard oaks in Gainesville, Florida from 1996 to 2000. Even when defoliation was not severe, the falling frass and large numbers of caterpillars were a major concern for many homeowners. Little is know about this species beyond the few pages published in the 1996 book Wild Silk Moths of North America (Tuskes, Tuttle & Collins. Ithaca: Comstock Pub. Assoc.). In 1999 we started a research project to learn more about the yellowstriped oakworm. Our research objectives are to document and describe the biology, dynamics, behavior and control of this insect, noting especially the similarities and differences with the closely related orangestriped oakworm, Anisota senatoria.

Please Help - The Gainesville outbreak was located in the area north of NW 39th Ave between highways SR-121 and US-441. We would like to know of other areas within the city and across the southeastern United States where this insect has been or currently is a pest. If you can help us, please email either John Foltz or David Serrano with details of where and when you have encountered this insect.


Illustrated Life History

Female Moth
Female of Anisota peigleri Moths are present during late August and early September. The female, illustrated here, is reddish-orange in color and about 3/4 - 1 inch 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.

Male Moth
Adult male of Anisota peigleri Males are smaller than females, the body ranging from 5/8 to 3/4 inch 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 which they use to locate females by tracking the pheromones females release during their "calling."

Adult Male on Leaf
Male of Anisota peigleri These moths are easily approached. During the August-September flight period they may be found resting on shrubs and on trunks of trees. They are also commonly seen resting on the walls of buildings.

Female and a Few Eggs
Female and eggs of Anisota peigleri Females lay their eggs on the underside of oak leaves in masses ranging from 10 to 374 eggs. The average mass contains about 150 eggs. Egg masses are generally located at the ends of the lower branches of the tree canopy. Sometimes a female can be found resting on the base of the leaf after the eggs are laid.

Eggs and Newly Hatched Larvae
Eggs and neonates of Anisota peigleri Eggs are yellow to orange-yellow in color (black when parasitized), spherical in shape, and about 1 mm in diameter. The eggs take from 1 to 1 1/2 weeks to hatch. The neonates, present in mid September, are yellow with a black head and two prominent horns arising from the second thoracic segment.

Neonates Feeding
Larvae of Anisota peigleri Caterpillars from an egg mass stay together during the early instars. The small caterpillars consume only the soft portions of the leaf, leaving behind the leaf skeleton. Larval clusters can be easily located by looking in the vicinity of skeletonized leaves.

First and Second Instars
Larvae of Anisota peigleri After several days of feeding and growing, the neonates shed their head capsule and skin and become second stage larvae. The second stage caterpillars retain the yellow color.

Third and Fourth Instars
Larvae of Anisota peigleri During the third and fourth stages the caterpillars change from the yellow to a black color. Eventually, larvae become black-bodied with yellow stripes running down their sides.

Fully Grown Larva
Larva of Anisota peigleri In late October the larvae are fully grown and may be 2 inches long. All have the black coloration with yellow stripes. The black horns arising from the second thoracic segment are still prominent. A row of small spines runs down the length of the body behind each of the horns.

Pupal Stage
Pupa of Anisota peigleri Pupae, like adults, vary in size according to sex. Male pupae range from 3/4 to 1 inch and female pupae range from 1 to 1 1/4 inch in length. The pupae reside in the soil about 2-3 inches deep, "overwintering" for about ten months. Moths emerge the next year to begin the cycle again.

Defoliation 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 insect populations:

  • Provide appropriate water and nutrients to the tree throughout the growing season.
  • Watch for and remove eggs and young colonies from the lower branches.
  • If large numbers of caterpillars are too high for removal, contact a pest control operator for application of an appropriate insecticide.

For information on other forest and shade tree insects in Florida

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Created 10/11/99 by David Serrano and John Foltz. Last modified 28 June 2002.