Gulf Fritillary

Agraulis vanillae — the Gulf fritillary — is one of the most striking butterflies in the southern US and a member of the tropical longwing tribe Heliconiini. The species is widespread across the southern US (especially Florida, Texas, and the Gulf Coast), Mexico, Central America, and South America, with seasonal range expansion north to the central US in summer. Adults are 6-9 cm wingspan with bright ORANGE UPPERSIDES marked by bold black spots on both forewings and hindwings, and the species' diagnostic feature: BRILLIANT METALLIC-SILVER-AND-CREAM SPOT PATTERNS on the UNDERSIDE of the hindwings — large irregular silver spots that look like polished mirror chips embedded in the wing surface. The metallic silver color is created by structural coloration (light interference from microscopic wing scale ridges) rather than pigment, and the spots flash dramatically with every wingbeat. The species is one of the most-photographed butterflies in southeastern US macro nature photography because of the dramatic silver wing pattern. The Gulf fritillary is a HELICONIINI — a tribe within family Nymphalidae that includes the longwing butterflies of Central and South America (zebra longwing Heliconius charithonia, postman butterflies Heliconius spp., red lacewing Cethosia spp., and other tropical longwings). The Heliconiini share a suite of distinctive biological features: long narrow wings, bright warning coloration, sequestration of toxic compounds from larval host plants, and the ability of adults to feed on POLLEN as well as nectar (a behavior unique to heliconiine butterflies among Lepidoptera). The Gulf fritillary's larval host plants are exclusively PASSION FLOWERS (Passiflora species — passionvine, maypop, native and ornamental varieties). Passion flowers contain CYANOGENIC GLYCOSIDES — compounds that release hydrogen cyanide when chewed by herbivores — and most insects cannot tolerate the chemistry. Gulf fritillary larvae have evolved tolerance for the cyanogenic compounds and SEQUESTER THEM in their body tissues, retaining the toxicity through pupation into the adult stage. Adult Gulf fritillaries are therefore CHEMICALLY DEFENDED — bird predators that attempt to eat Gulf fritillaries learn (after one or two unpalatable encounters) to avoid the bright orange-and-black coloration. The species is widespread in the southern US, harmless to humans, and a major beneficial pollinator across the southeastern US and Caribbean.