Gray Hairstreak © Brian Kenney

Hairstreaks and Elfins

Description 1-1 1/4" (25-32 mm). Above, deep slate-gray with orange spot on HW; female browner. Below, dove-gray; straight, thin FW and HW red and black midband lined with white; bold orange and blue patches above tail, black spot at HW outer angle (tornus). Abdomen has orange sides.

Similar Species Avalon Hairstreak sandy-buff below with reduced bands and orange. Other similar hairstreaks are browner or lack bright orange spot above.

Life Cycle Egg pale green. Caterpillar variable, usually grass-green to translucent green, with white to mauve diagonal side stripes; various host plants are nearly 50 different plants in over 20 families; host plants include corn (Zea mays), oak (Quercus), cotton (Gossypium), strawberry (Fragaria), and mint (Lamiacea), legumes and mallows preferred. Chrysalis brown with copious black mottling.

Flight Variable, number of broods increasing southward: 2 in North, 3 or more in South; April-October.

Habitat Open deciduous woods, coastlines, roadsides, chaparral, old fields, parks, vacant lots, and other open spaces.

Range British Columbia to Maritimes, and south to Baja California, Florida; also to Venezuela and Colombia.

Discussion Absent only from the far North, the Gray Hairstreak is one of the most generally distributed butterflies. The caterpillar is known regionally as the "cotton square borer," and has upon occasion damaged commercial bean, hops, and cotton crops. Gray Hairstreaks now occur in all the California islands, having colonized Catalina Island, stronghold of the Avalon Hairstreak, in 1978. By 1979 both species from Catalina showed atypical variation, implying possible hybridization between them. Until now, the Gray Hairstreak has appeared to exclude the Avalon Hairstreak from the other California islands; therefore, scientists and conservationists are watching the Gray Hairstreak's influx to Catalina with apprehension.