Megalopyge opercularis

(J.E. Smith, 1797)

southern flannel moth, puss caterpillar, asp, Italian asp, fire caterpillar, woolly slug, opossum bug, puss moth, tree asp, asp caterpillar

Megalopyge opercularis is a in the , notable for its highly venomous larval stage and strikingly different form. The , known as the puss caterpillar, is densely covered in hair-like that conceal venomous capable of delivering extremely painful . The adult, called the southern , is covered in soft fur ranging from dull orange to lemon . The has two annually in much of its range, with late-season sometimes in .

Megalopyge opercularis bissesa by no rights reserved, uploaded by Sinaloa Silvestre. Used under a CC0 license.

Megalopyge opercularis bissesa by (c) Sue Carnahan, some rights reserved (CC BY), uploaded by Sue Carnahan. Used under a CC-BY license.

Pronunciation

How to pronounce Megalopyge opercularis: /ˌmɛɡəˈlɒpɪdʒi oʊˈpɜːrkjələrɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

The puss is distinguished from similar Megalopyge by its tail that extends well beyond the body, unlike M. crispata which lacks this distinctive tail. Among stinging caterpillars, it is uniquely recognized by its dense, soft, fur-like appearance concealing venomous —resembling a small mammal rather than a typical caterpillar. The southern is identified by its compact, heavily furred body and small relative to body size. Color variation in is extensive, making size and tail structure more reliable than coloration alone.

Images

Habitat

Found in wooded areas, forests, and suburban landscapes; feed on foliage of various trees and shrubs including oak, elm, wild plum, apple, birch, hickory, pecan, persimmon, and rose; also occurs on garden plants such as roses and ivy.

Distribution

Eastern United States from extreme southeastern Virginia south to Florida; throughout the Southern United States; Mexico; parts of Central America; parts of South America.

Seasonality

Two annually: one in summer and one in fall; late-season may remain in throughout winter, emerging as in late spring; adult activity peaks in spring and summer depending on geographic location.

Diet

feed on leaves of various including oak, elm, wild plum, apple, birch, hickory, pecan, persimmon, and rose; also reported on garden plants such as roses and ivy.

Host Associations

Quercus spp. - larval oak
Ulmus spp. - larval elm
Prunus americana - larval wild plum
Malus spp. - larval apple
Betula spp. - larval birch
Carya spp. - larval hickory
Carya illinoinensis - larval pecan
Diospyros virginiana - larval persimmon
Rosa spp. - larval rose
Hedera spp. - larval ivy

Life Cycle

with four stages: , , , . Larva passes through multiple ; early instars have curly, cottony appearance, middle instars develop disheveled look without distinctive tail, final instar has pronounced tail extension. occurs in with hair pockets and . Two per year in most of range; late fall larvae may in cocoons over winter, emerging as adults the following spring.

Behavior

are slow-moving and feed solitarily on foliage; the dense hair-like serve as defensive concealment for venomous beneath. are and attracted to light. The 's appearance of a small, furry mammal is a form of protective that may deter some .

Ecological Role

as , consuming foliage of various trees and shrubs; serves as for various and despite defenses; may contribute to though specific role is not well documented.

Human Relevance

The puss is considered one of the most venomous caterpillars in North America. Contact with the concealed causes immediate, severe pain described as comparable to broken bones or blunt-force trauma, with including burning, swelling, nausea, headache, abdominal distress, rashes, blisters, and in severe cases chest pain, numbness, or difficulty breathing. The condition is termed erucism or urticarial dermatitis; M. opercularis is the most commonly reported source of caterpillar in the United States. Medical attention is recommended for reactions. First aid involves removing embedded spines with cellophane tape; various remedies including ice packs, antihistamines, and topical treatments have been reported with varying success.

Similar Taxa

Megalopyge crispataSimilar appearance and venomous ; distinguished by lack of tail extension beyond body in M. crispata versus pronounced tail in M. opercularis
Norape ovina with similar dense hair-like and venomous ; distinguished by different coloration and preferences including black
Automeris ioIo with prominent venomous ; distinguished by clusters of branched spines radiating from body rather than dense fur-like covering
Hemileuca spp.Buck with venomous ; distinguished by prominent branched spines and preference for oak foliage without dense fur-like concealment
Phobetron pitheciumHag or monkey with unusual fleshy appendages; distinguished by bizarre lobes rather than uniform furry covering

More Details

Venom mechanism

The urticating are hollow, barbed structures that break off upon contact and embed in skin, delivering through a gland at the spine base. The venom composition includes multiple bioactive compounds contributing to intense pain and inflammatory response.

Defensive mimicry

The 's resemblance to a small mammal (Persian cat) represents protective that may reduce by visual , while the concealed provide active chemical defense against tactile predators.

Parasitoid associations

The ichneumon Calliephialtes grapholithae has been reared from M. opercularis; this wasp typically attacks concealed and the 's likely provides such concealment.