Spotted Wing Drosophila
The spotted wing drosophila (SWD) (Drosophila suzukii) is an invasive fruit fly of East Asian origin that has been detected in South Carolina (Spartanburg, Aiken, Newberry, Saluda, Lexington, Richland, Beaufort and Bamberg counties) and now can be found throughout the U.S. SWD has caused significant economic damage in cherries, strawberries, blueberries, raspberries, and blackberries. Tart cherries, strawberries, peaches, nectarines, plums, and figs may also be attacked.
Unlike other vinegar or fruit flies that lay their eggs on past ripe or rotting fruit, SWD lay their eggs inside ripening, damaged, or split soft-skinned fruit right before harvest. The small (2-3 mm) light brown female flies lay 1 to 3 eggs in the soft skin of ripe or ripening fruit. Other SWD females may visit the same fruit and lay additional eggs. Females may lay up to 7-16 eggs per day, leaving telltale scars on the surface of the fruit. On some fruit there is no visible sign of attack, only after the fruit is harvested and prepared for eating.
When the eggs hatch, the larvae feed inside the fruit and within a week cause the fruit to collapse, turn soft, and rot. The larvae exit the fruit, pupate, and in 3 days to two weeks emerge as adult flies. Adults may live as short as 1 to 2 weeks or as long as 3 to 9 weeks. In their native Japan, SWD produce 13 generations per year; experts predict 10 generations per year in the U.S., depending on the climate.