Recently, Midpen ecologists took to a hill in Pulgas Ridge Open Space Preserve in hopes of finding endangered bay checkerspot butterflies (Euphydryas editha bayensis), an endemic species that can only be found in Santa Clara and San Mateo counties.
Bay checkerspots live almost exclusively in serpentine grasslands near their host plant dwarf plantain (Plantago erecta). They also frequent sloping hills and mountains where they can move to a cooler side of the hill when its warm, and a warmer side when it’s cold.
As caterpillars, they feast on dwarf plantains. When they become butterflies with characteristic white, black and reddish-orange spots, they graduate to drinking nectar from wildflowers like tidy tips (Layia platyglossa), California goldfields (Lasthenia californica) and fiddlenecks (Amsinckia intermedia).
At Pulgas Ridge Preserve, Midpen ecologists spotted three butterflies, none of which were bay checkerspots. Their habitat is threatened by the growth of non-native invasive plants, habitat degradation caused by urban development and wildfire. Midpen staff plan to conduct another survey for the bay checkerspot as the weather warms up.