What is Spotted Wing Drosophila?
Spotted Wing Drosophila (SWD) is a small vinegar fly (about 0.1 inches in length) that for the last two years has been causing economic damage to berries, grapes, and softer-fleshed fruit such as peach in several areas of the US including the Midwest. It is native to Japan, so this insect is invasive to the US. SWD was detected in Missouri in late June through a monitoring system that was deployed by the LU Integrated Pest Management Program.
Why Should I be concerned about SWD? Is it that bad?
SWD very quickly became a devastating pest of berry crops in Missouri. Adults were first detected in monitoring traps in late June, 2013. By early August, infestations to blackberry fruits had already been reported. By mid August, SWD was reported infesting crops state-wide. In addition to small fruit crops, this invasive insect pest also attacks some stone fruits (cherry, nectarine, peach), high tunnel tomatoes, and wild hosts (including pokeweed, autumn olive, crabapple, nightshade, Amur honeysuckle, and wild grape). Raspberries, blackberries, blueberries, elderberries and grapes are at the greatest risk. Picture 1 shows larvae leaving out blackberry fruits.
SWD flies look similar to the small vinegar flies that are typically found around or on fermenting fruits and vegetables. SWD males have one black dot on each wing and females do not have dots in their wings; they have a serrated egg-laying device called an ovipositor, to cut a slit into the skin of intact fruit to lay their eggs (Picture 3). This makes SWD a more significant pest.