common name: goatweed butterfly, goatweed emperor, goatweed leafwing
scientific name: Anaea andria Scudder (Insecta: Lepidoptera: Nymphalidae: Charaxinae)
The goatweed butterfly is an attractive, fascinating and widespread species that is not often observed by the general public because of its cryptic coloration and somewhat spotty distribution within its range. Both larvae and adults are cryptically colored. Adults play dead when handled. This species provides dramatic examples of adaptive coloration and behavior to escape predators in both the larval and adult stages.
The goatweed butterfly is widely distributed throughout the southern Midwest and South ranging from West Virginia to Kansas and south to Texas and Central Florida.
The wingspread of goatweed butterflies is 6.0 to 7.6 cm with males being slightly smaller than females. The upper surface of the wings of adult goatweed butterflies exhibit sexual dimorphism in both shape and color. The wings of males are more or less uniformly orange brown with a dark margin. The wings of females have an irregular lighter submarginal band with broad darker margins. The apex of the forewing is hooked (falcate) and each hind wing bears a short, pointed, backward-projecting tail. Both sexes exhibit marked seasonal dimorphism in wing shape. In the summer forms, the forewing apex is less hooked and the hindwing tail is shorter than in the winter form. They also exhibit seasonal color dimorphism. Summer males are slightly less orange with a narrower marginal band. Summer females are lighter in color than winter females. The undersides of the wings mimic dead leaves and are similar in both sexes.
Both the appearance of the adult seasonal forms and reproductive diapause in the winter forms are controlled by responses of the larvae to photoperiod (daylength). Larvae exposed to short photoperiods during late summer and early fall produce winter form adults that are in reproductive diapause.
adult female (summer form)
adult male (summer form)
resting goatweed butterfly
Eggs are spherical and greenish-cream in color. Full-grown larvae are approximately 3.8 cm in length and are grey-green with many minute tubercles covering both the head and body. The head also has a small number of larger orange tubercles. The color and tuberculation of the larvae match the surface texture and appearance of twigs of some common host plants. Pupae are light green with darker green lines simulating a leaf-like texture. There is a small heavily sclerotized black anal ring just below (anterior to) the cremaster.
egg
full grown caterpillar
pupa
The goatweed butterfly has two flights per year in the North with possibly three or four flights in parts of the South. Their flight is swift and erratic. Overwintering adults mate in the spring. Males wait for females in clearings or on ridge tops. Adults feed on sap flows, decaying fruits, and dung. Larval hosts for the goatweed butterfly are various species of plants in the genus Croton (Euphorbiaceae). A commonly used host-plant species in central Florida is silver croton, Croton argyranthemus Michx. a common inhabitant of long leaf pine (Pinus palustris Mill.) high pine communities. Goatweed butterflies are also found in other habitats - including open wooded areas, swamps, prairie groves and along streams.
First and second instar larvae eat the leaf blade away from the midrib and rest at the tip. They attach fecal pellets with silk to their backs and to the base of the leaf midrib - probably to repel ants and other predators. Older larvae fold and silk the sides of leaves together and hide inside with their heavily sclerotized heads blocking the entrance to the leaf roll.
silver croton
second instar larva
larvae
The pine sandhill and scrub habitats that support silver croton are rapidly diminishing in Florida because of development. It is expected that goatweed butterfly populations will continue to decline locally as a result of this urban encroachment.
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Authors: Donald W. Hall and Jerry F. Butler University of Florida
Photographs by: Jerry F. Butler (Anaea andria photos) and Donald W. Hall (Croton argyranthemus photo)
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-55
Publication Date: September 1998. Latest revision: May 2007.
Copyright 1998-2007 University of Florida
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