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Spotted Wing Drosophila Identified in Central Oregon
Well, there’s a new pest in town that is particularly attracted to these fruits. It is the Spotted Wing Drosophila or Drosophila suzukii. This pest was first found in Oregon in 2009 but up till now has not been seen in Central Oregon. In September there was positive identification of it in Redmond.
This pest, actually a vinegar fly, attacks many types of fruits, the ones mentioned before are the preferred hosts but it will infest injured fruit like grapes, tomatoes, apples, Asian pear and more. Vinegar flies, frequently mistakenly called fruit flies, are usually attracted to overripe or rotting fruit. You often see them around compost piles or trash containing rotting fruit remnants. The Spotted Wing Drosophila, however, is attracted to fruit as it is ripening. The female lays eggs into the fruit. After a couple of days the fruit begins to get soft at the injection site. After hatching from the egg stage a small, whitish maggot grows feeding throughout and causing the fruit to soften even more. Sometimes a gray mold will form at the injection site. After feeding for 5-7 days the maggot pupates, usually in the fruit, for another 4-5 days when it emerges as an adult fly.
The SWD is about 3-4mm and can be identified by specific characteristics. The male has black spots near the tip of the wings (see picture below).
The female has an ovipositor, at the end or her abdomen, used to place eggs into the fruit.
SWD is an important pest to control both commercially and in the home landscape because it attacks and ruins fruit just as it is ripening. So how do you control this pest? The most important step is to pay attention. Monitor your fruit often and keep it picked. Do not allow fruit to stay on the plant once it is ripe. If you notice small vinegar flies around the plants try to observe what they look like, look specifically for two black or faded spots near the tips of the wings. If you notice soft spots in fruit that you are harvesting to eat, break it open and place it in a clear jar. Let it sit for 5-10 minutes then look to see if you see any small, white maggots crawling around or on the fruit. Or bring samples of the fly and fruit to your county Extension office for identification.
Oregon State University has a publication titled “Protecting Garden Fruits from Spotted Wing Drosophila” with information on how to make simple traps useful in monitoring and trapping this pest, as well as control measures. Check out these article for more information.