BEND, OR -- Central Oregon will be home to the California Tortoiseshell butterfly for the next four to six weeks. The distinctive yellow wings with the black borders have been spotted around the region in the past week, as they begin their migration from the deserts of California and Arizona.
Ralph Berry is a retired Professor Emeritus of Entomology for Oregon state University tells KBND News, "The numbers depend on the flowers in Arizona and California, to build up that population, that turn into adults that then, migrate northward. It's a good year for flowering plants in the desert area, and so that stimulates the production of a lot more adults." He adds, "It's been awhile since we've seen this number, we always have some. Primarily, keyed with the host plant. The adults need to feed on nectar, from the flowers from different plants, and then of course, they lay their eggs on snowbrush or buckbrush."
He says Central Oregon native plants play a crucial role in the species' life-cycle, "The adults will lay eggs on snowbrush, and then the caterpillars will feed on the leaves, and then they'll drop to the ground and they'll form a pupa stage, the adults will emerge, and they'll lay eggs back on the snowbrush."
Berry says the migration always starts in April, and it's common to see them flying together in a kaleidoscope.