Bay Checkerspot Butterfly

Euphydryas editha bayensis (Sternitzky, 1937)
Date of listing: 1987
Federal Status: Threatened
State Status: None

It is ironic that the insect on which Paul Ehrlich based his idea of metapopulations, now a paradigm for conservation of endangered species, has since become threatened itself. The Bay Checkerspot Butterfly has experienced serious declines in its populations since the mid-1980s. Because this species has long enjoyed the attention of numerous biologists, its decline was quickly realized prompting its listing as threatened in 1987.

The Bay Checkerspot has an interesting life cycle which may include a few different host plants. Following mating in mid-spring, the female butterflies lay their eggs on a native plantain, Plantago erecta. The eggs hatch and the larvae feed on this host until either they have developed to a point at which they may enter dormancy or the host has begun to dry up from the summer heat. If the plantain is not sufficient for development the larvae may move onto one of two species of owl’s clover (Castilleja densiflorus or C. exserta) which remain palatable for a longer period. Generally, one season is not sufficient for completion of development and the larvae must enter dormancy until the following winter when the rains allow plant growth to begin again. The larvae then emerge to feed for a little longer, pupating in late winter. The adults emerge shortly thereafter.

Populations of the Bay Checkerspot historically inhabited numerous areas around the San Francisco Bay including the San Francisco peninsula, the mountains near San Jose, the Oakland hills, and several spots in Alameda County. Most of these have apparently disappeared due to the explosive development of the Bay area in the past century. Populations are now known only from San Mateo and Santa Clara counties. Changing disturbance regimes (i.e. fire, grazing) as well as introduced grassland plants have caused declines in host plant populations. In Santa Clara County much of the butterfly’s habitat is on property owned by a landfill corporation. An agreement worked out among the owner, the city of San Jose, and conservation advocates has resulted in the protection of much of this habitat in exchange for permitted, conscientious development of a small portion of it. In addition, the landowner has provided funding for the establishment of a butterfly preserve and for research towards successful management of the Bay Checkerspot.

For further reading:
Murphy, D.D., 1988. Ecology, politics and the Bay Checkerspot butterfly. Wings 13(1): 4-8, 15.

Murphy, D.D., 1988. The Kirby Canyon Conservation Agreement: A model for the resolution of land-use conflicts involving threatened invertebrates. Environmental Conservation 15(1): 45-48.

Murphy, D.D. and S.B. Weiss, 1988. Ecological studies and the conservation of the Bay Checkerspot butterfly, Euphydryas editha bayensis. Biological Conservation 46(3): 183-200.


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