Tortoiseshell Butterflies

The California Tortoiseshell (Nymphalis californica) in the above picture, Compton Tortoiseshell and Mourning Cloak represent the Nymphalis genus.

California Tortoiseshells are Western butterflies, one of many orange brushfoot species, and one of the first spring arrivals. The black border that surrounds the wings is one helpful identification trait.

During certain years, California Tortoiseshell populations erupt, and large numbers, often reaching the thousands range, migrate. At these times, a mile long drive along a Western mountain pass might mean driving through a group of ten thousand Tortoiseshells.

The caterpillars feed on lilac plants.

The Mourning Cloak (Nymphalis antiopa), although in the same genus as the California Tortoiseshell, looks substantially different.

The caterpillars feed on leaves from a variety of trees, including willow and elm, which partially explains it wide spread distribution.

In good light, the otherwise dull looking species shines. The brown wings with yellow edging and blue spots help provide camouflage for the butterfly as it nectars on tree sap.

Many adults hibernate during the winter, becoming one of the first species seen when the weather warms during spring.

It's a widely distributed North American species found from coast to coast, including Canada.

Milbert's Tortoiseshell (Aglais milberti), one of two Aglais species is predominantly a northern species, inhabiting marsh areas in Alaska, Canada and the northern United States.

Yellow and orange coloration spice up otherwise dull brown wings.

The caterpillars feed on stinging nettles and adults enjoy nectaring on fruit, sap and occasionally flowers.

© 2002-2011 Patricia A. Michaels