Where the butterflies roam
Monarch butterflies (Danaus plexippus) are well-known for their long-distance migrations. Monarchs east of the Rocky Mountains spend their winters in Mexico, while those west of the Rockies head for the California coast. But there are others, like the painted lady (Vanessa cardui) and the California tortoiseshell (Nymphalis californica) that also make annual treks over hundreds of miles in response to the changing seasons.
But other butterflies, like blues, coppers, hairstreaks, and metalmarks, hardly move at all. Individuals and their offspring may never leave a single meadow or dune for many generations. Their caterpillars often feed on a single species of plant found in a particular habitat many miles from other similar habitats. Some even have intimate relationships with ants, whereby the ants take the larvae into their nests and care for them. Because of these particular (and peculiar) life histories, many species and subspecies of butterflies in the family Lycaenidae have very restricted distributions and are listed as either threatened or endangered. One subspecies, the Xerces blue (Glaucopsyche lygdamus xerces) that once lived in the coastal dunes of California, went extinct in the 1940s. Even the once common and widespread monarch has suffered massive population declines in the past two decades.
New conservation efforts, however, are turning the tides for these imperiled imps of the sky. Captive rearing and release of threatened species of blues and checkerspots are establishing new populations to protect against local extirpation. Neighborhood programs to propagate native host plants have connected populations of green hairstreaks that were once isolated from each other. And concerned citizens across the country are planting milkweed to feed hungry monarch caterpillars.
To aid this cause, our team at CalBug has been busy photographing butterflies in our collection. These historical records tell us how butterflies have responded to climate, land use, and other environmental changes over the past 100 years. With your help, we can map these changes over time and better focus our restoration efforts. And since we include the name of each species in the corner of each photo, and photos pop up in a random order, each new image is like a flashcard to help you learn to identify butterflies!
by Peter Oboyski
Lucas Foglia, c/o Essig Museum
Specimen images, c/o Essig Museum