Blue alfalfa aphid: A new pest in the imperial valley

Specimens of this new aphid were unknowingly collected by one of the authors from alfalfa near Bakersfield, California in 1974. The samples were taken to detect lygus bug parasites and the aphids in the samples were not counted. Fortunately, the samples were preserved for other observations. When the new aphid reached outbreak numbers in 1975, the Bakersfield samples were reexamined and specimens of the new aphid were identified by R. C. Dickson, U.C. Riverside.