California Dogface Butterfly (Zerene eurydice)
By Evan Cole, Pollinator Partnership
In 1972, California designated the California dogface butterfly as its state insect. Also known as the “dog head butterfly”, the California dogface butterfly is endemic to California, found only between north-central California and Baja California, between the Sierra Nevada and Coast Ranges. It is considered very rare or local throughout its range.
The eggs of the California dogface butterfly are ribbed, and flat on one side. The eggs are green or yellow at first, becoming crimson as they develop. Larvae hatch from the eggs and eventually metamorphose into adult butterflies. The California dogface butterfly has large eyes and scaly wings, which assists them in flying and heat insulation. Most of its body is covered in small hairs, called setae, which are used to sense vibrations. The average forewing length of the California dogface butterfly is about 22-31mm. This species displays extreme sexual dimorphism, with each sex displaying distinct markings and colorations. The male’s forewings feature a yellow to peach colored shape resembling a dog’s head, with dark purple to black coloration along the edges, and the hind wings are orange with a yellow fringe near the abdomen. The female’s forewings are usually entirely yellow, with a black spot on the upper wings, and the hind wings are solid yellow.
There are two brooding periods for the California dogface butterfly. The first brood lasts from April to July, peaking in June, and the second brood flies between August and October. It is relatively rare to catch a glimpse of a California dogface butterfly, because they often fly 10-20 feet above ground, except when stopping to feed on a low flower, and are exceptionally fast.
As a caterpillar, the California dogface butterfly mainly feeds upon the leaves of the false indigo plant (Amorpha californica). The primary food source of the adults is the flower nectar from plants of the mustard family (Brassicaceae). It is an incredibly important pollinator for these, as well as a number of other California native plants, including California buckeye, thistles, and tall blue verbena. Interestingly, the California dogface butterfly has frequently been observed to prefer purple flowers.