Large-Scale Migrations of the Painted Lady Butterfly, Vanessa cardui (Lepidoptera: Nymphalidae), in Inyo County, California, during 1991
Detailed observations on significantly large migrations of Vanessa car- dui during 1991 in Inyo County, California, are presented, with special emphasis on their complex behavioral activities. The build up and mass exodus at a pop- ulation center near Bishop are chronicled and provide insights into why some butterflies migrate. A directional shift from northward to southward migration occurred during the summer. The migration phenomenon in this species appears to be dependent upon larval stress subsequently influencing adult juvenile hor- mone levels. This behavior likely evolved during the Upper Miocene as an ad- aptation to avoid seasonally unfavorable arid conditions.
Giuliani, Derham and Shields, Oakley
"Large-Scale Migrations of the Painted Lady Butterfly, Vanessa cardui (Lepidoptera: Nymphalidae), in Inyo County, California, during 1991,"
Bulletin of the Southern California Academy of Sciences:
Available at: http://scholar.oxy.edu/scas/vol94/iss2/4