The California Tortoiseshell is a very rare migrant from the west. It has been recorded from Michigan, New York, Pennsylvania, and Vermont in the east as well as most of the western states, and was listed in Ebner’s 1970 Butterflies of Wisconsin.
Above, an orange butterfly, with wide black margins and a few small black spots on the forewings. Below, this species is brownish/gray and is similar to many of the commas, but lacks the silvery spot in the middle of the hindwing that characterizes those species.
The Compton Tortoiseshell is somewhat similar, but is larger, does not have a wide dark margin on all four wings, and has larger dark spots in the forewing. The small dark spots in the California Tortoiseshell make this species appear to have a more open appearance on the upper wings. Below, the California Tortoiseshell does not have a silvery comma-like mark like the Compton Tortoiseshell.
Woodland clearings and trails.
A very rare migrant from the west.
In the west, this species has large migrations and thousands of these butterflies may be seen in a single day. In Wisconsin, the species is very rare.
Boulder Co., CO, June 30, 2009.