A historic account of the invasion of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in the continental United States, with remarks on their identification.

BACKGROUND: Drosophila suzukii is an oriental species first reported outside Asia from Hawaii in 1980. The first confirmed records for the continental United States were made in 2008 in California. The identification of this pest is difficult because very few published resources exist.
RESULTS: It has since been recorded in Oregon, Washington, British Columbia, Alberta, Manitoba, Ontario, Quebec, Utah, Michigan, Wisconsin, Louisiana, North Carolina, South Carolina and Florida. Males are relatively easy to identify by the black apical wing spots and the single row of combs on the first and second tarsal segment of the fore leg. The male genitalia are also very characteristic and will aid in identifying teneral specimens. Females can be identified by the large ovipositor, which is 6-7 times as long as the diameter of the spermatheca. Immature stages can only be identified by molecular techniques.
CONCLUSION: Although this species has been recorded from many US states and Canadian provinces, it has not been established in all of these places, and the main economic damage is restricted to the western part of North America. With the characters laid out in this paper, it should be possible to identify the pest with high certainty.