Gulf Fritillary Caterpillar

The Gulf fritillary caterpillar is the larval stage of a brilliant orange butterfly common throughout the southern United States and into Central and South America. It is a passionflower specialist, feeding almost exclusively on vines in the genus Passiflora, which contain toxic compounds the caterpillar sequesters as a defense inherited into adulthood.

Gardeners who grow ornamental passionflower vines often encounter this caterpillar in large numbers, as females frequently lay many eggs on a single host plant.

• Body is bright orange to yellow-orange with fine black speckling
• Rows of long, branched black spines (scoli) run the length of the body, giving a bristly appearance
• Head is black with short spines
• Body is soft and glossy rather than fuzzy despite the spiny look
• Spines look sharp but are not rigid or hard
• Distinguished from the similar zebra longwing caterpillar (which is white with black spines) by its solid orange coloration

This species ranges across the southern United States, Mexico, Central America, and much of South America, and has also become established in parts of the world where passionflower has been introduced, including Hawaii and parts of Australia. Caterpillars are found wherever passionflower vines grow, in gardens, fence lines, thickets, and open woodland edges, active nearly year-round in frost-free areas.

The caterpillar feeds exclusively on passionflower vine leaves and can strip a vine bare when populations are dense, making it a recognized garden pest of ornamental Passiflora. By feeding on a toxic host plant, it sequesters defensive compounds that make both the caterpillar and the resulting butterfly distasteful to many predators, a strategy advertised through its bright warning coloration. It contributes to local food webs as prey for insects and birds tolerant of its chemical defenses, and the adult is an important nectar pollinator.

Females lay small yellow, ridged eggs singly on passionflower leaves, tendrils, or stems. The larva passes through five instars over about two weeks, growing rapidly on its host plant. The mature caterpillar forms a mottled brown chrysalis that resembles a dead curled leaf, suspended by a silk girdle from a stem or nearby structure. In warm climates the species breeds continuously with multiple overlapping generations per year, while in cooler areas it may not overwinter successfully and relies on recolonization.