In 1929, California became the first state to choose an insect to represent the state. They chose the California Dogface Butterfly (Zerene eurydice) by conducting a statewide poll to all active entomologists in the state. Not until 40 years later would this unique butterfly become the official state insect of California. The Dogface Butterfly has a range from San Diego County to Sonoma County and is usually found in mountain and foothill locations. The host plant for this butterfly is False Indigo (Amorpha californica). The butterfly uses this plant as a nectar source for adults, a place to lay their eggs and a food source for the young caterpillars.
At Placer Land Trust’s Shutamul Bear River Preserve, located in Auburn, an interesting discovery was made a few years ago by local naturalist/birdwatcher and practicing amateur lepidopterist Deren Ross. With a growing interest in butterflies and the hope of one day seeing the California Dogface butterfly in the Auburn area, Ross began studying the life history of the butterfly. He learned the key to finding this butterfly was to find the host plant — False Indigo.
After finding two very old records of this uncommon plant in Placer County, he contacted Nick Jensen at the California Native Plant Society. To his surprise, found two more records from 2006 on a recently acquired Placer Land Trust property on the Bear River known as Shutamul Bear River Preserve. He went on a site visit in the fall of 2008 and found only leafless twigs which he could not identify at that time. Upon further investigation he found it was in fact False Indigo, and it was so abundant on the preserve he was sure the butterfly would be present as well. Ross visited the Shutamul Preserve only once a year for the next two years and during those visits was able to see many Dogface Butterflies. He later learned from Professor Art Shapiro at UC Davis that the life history of the Dogface butterfly was not well understood especially for the over-wintering adults. Ross saw this as a great opportunity to conduct a scientific study to document the life-cycle of this butterfly.
In June 2011, Ross began going out to the Shutamul Preserve weekly to conduct male/female butterfly counts and behavior patterns. It proved to be a very exciting study; eggs were observed being laid on the False Indigo and then caterpillars got busy munching away at the plant. Previous research indicates the butterfly has two broods per year: one brood from April to July (adult life-span 3-4 months) and a second in August to October (adult life-span 6-8 months). The adults from the last brood overwinter in a state of hibernation until emerging again in early spring and mating.
During the month of June, we host small group tours to see the butterflies. Check out the video below for a virtual tour!
