The California Tortoiseshell is a bright orange-and-black butterfly of western mountains that periodically irrupts in enormous numbers — millions of individuals migrating through mountain passes together. Adults overwinter and emerge early in spring, feeding on tree sap and early flowers. Caterpillars feed gregariously on California lilac in dense colonies.
Habitat
Mountain brushlands and forests with California lilac
Diet
Larvae: Ceanothus (California lilac). Adults: tree sap, fruit, and nectar
How common
Common
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