Cassius Blue
Leptotes cassius theonus

Small butterfly with a wingspan to 1-3/8 inches. The upperside of the male is pale blue to bright blue with white fringes; that of the female is bluish-white to white with broad dark borders on the front wing and a dark spot on the rear margin of the hindwing. The underside of the hindwing is white with dark gray bands and two orange-rimmed black spots on the outer margin. The caterpillar has a black head; the body color varies from green with faint dark markings to patterned with faint white markings or red markings with white chevrons.
South Florida and southern Texas, West Indies, Mexico, Central America and South America. Strays to North Florida but is cold-sensitive.
Distribution and Abundance in Florida:
Adults and caterpillars present all year in South Florida; ranges to western Florida except in winter.
Hammock edges and open, disturbed sites.
The pale green, flattened eggs are laid singly on the flower buds, flowers and seed pods of the host plants.
Natural History:
Caterpillars sometimes are tended by ants; they attract the ants with secretions from a gland on the dorsal surface of the seventh abdominal segment. Adults often are feed near the ground, but sometimes nectar high up in trees. Females flutter in flight; males fly faster and more erratically. Pupae make a noise with a scraper and file in the dorsal cleft between the fifth and sixth abdominal segments.
Caterpillars feed on the flowers, buds, and immature seeds of host plants. Native larval host plants include the cultivated trees Jamaica-dogwood (Piscidia piscipula) and wild-tamarind (Lysiloma latisiliquum), the shrubs cat's-claw (Pithecellobium unguis-cati) and Florida Keys blackbead (Pithecellobium keyense), the wildflower eastern milkpea (Galactia regularis), and the vine downy milkpea (Galactia volubilis); cat's-claw, Florida Keys blackbead and wild-tamarind are also nectar plants. Larvae also feed on the common nonnative landscape shrub leadwort (Plumbago auriculata), the weedy nonnative wildflower shakeshake (Crotalaria incana) and the invasive nonnative vine rosary-pea (Abrus precatorius). Other native host plants are the critically-imperiled crenulate leadplant (Amorpha herbacea var. crenulata) and the vines cowpea (Vigna luteola), Florida hammock milkpea (Galactia striata) and wild plumbago (Plumbago scandens). Native nectar plants include the cultivated shrubs pineland croton (Croton linearis) and wild-sage (Lantana involucrata), the wildflowers narrowleaf yellowtops (Flaveria linearis), snow squarestem (Melanthera nivea) and yellow joyweed (Alternanthera flavescens), and the vine yellowroot (Morinda royoc). Other native nectar plants include the wildflower southeastern sunflower (Helianthus agrestis). Weedy native nectar plants include Spanish-needles (Bidens alba var. radiata). Adults also feed on the invasive nonnative Brazilian-pepper (Schinus terebinthifolius).
This species is listed as Threatened Due to Similarity of Appearance (to the Miami blue) on the federal Endangered and Threatened Species list. For more information, go to the U.S. Fish and Wildlife Service's species profile. For additional information, visit the Florida Museum of Natural History's Florida Wildflowers & Butterflies website, the University of Florida/IFAS Featured Creatures website, Butterflies and Moths of North America and Butterflies of Cuba.

Beryn Harty, 2014
At Key West Botanical Garden
Beryn Harty, 2014
At Key West Botanical Garden
Beryn Harty, 2012
Beryn Harty, 2012
CJ McCartney, 2021. Mating pair on Butterflybush (Varronia bullata subsp. humilis)