Field observations on Harmonia axyridis Pallas (Coleoptera: Coccinellidae) in Oregon

A lady beetle native to Asia, Harmonia axyridis Pallas, is established in the Pacific Northwest of North America. Ten years occurred between the intentional release of beetles and the first observation of an individual on July 18, 1991, in Kings County, Washington. The beetle was extremely abundant in western Washington and Oregon throughout 1993-1994, where the species ranged from mideastern Washington, south to just north of the California/Oregon border, east to an elevation of 1371 m in the Cascade Mountains and west to the Pacific Coast. Field sampling confirmed the habits and habitats of H. axyridis as a generalist, semiarboreal, aphidophagous predator. Our records associate H. axyridis with 17 aphid prey species on 17 plant hosts. In western Oregon, H. axyridis co occurs with 11 species of native and 2 species of exotic aphidophagous coccinellids on trees and shrubs. In arboreal habitats, 70% of individual lady beetles and 82% of live adult coccinellid mass were represented by H. axyridis, while constituting only 4% of the coccinellids in alfalfa, clover, and peppermint. Adult H. axyridis dispersed to feeding sites from overwintering aggregations, which formed the preceding October, during March. At least two generations, with a partial to complete third generation, occur per year. Parasitism of field-collected adult beetles by Dinocampus coccinellae (Schrank) was less than 1%. (C) 1996 Academic Press, Inc.