A berry bad pest

Drosophila suzukii

Spotted wing Drosophila on strawberry. Photo courtesy Bev Gerdeman, Washington State University Extension

As if we needed more insect pests!  Now there is a new pest of berries that is spreading rapidly around the U.S.  The spotted wing Drosophila, Drosophila suzukii, is a native of Japan and was first discovered in California in 2008.  It has spread quickly to berry growing areas on the west and east coasts, as well as Canada, Michigan and the northeast.  It showed up in Colorado last year, and the first specimen in Texas was found by a faculty member in the entomology department at Texas A&M earlier this year.  Oklahoma discovered SWD in a berry farm in Tulsa this past June, and the pest has been in Louisiana since 2010.

While berries seem to be the most susceptible crop, and Texas may not be considered a huge berry state, the potential for damage here is still significant.  Besides raspberries and blackberries and strawberries, the fly attacks peaches, blueberries, plums, figs, persimmons and mulberries.  It can also survive on Osage orange, honeysuckle and snowberry and likely other berries native to Texas.  It does not seem to be a major pest on tomatoes (all Texas vegetable growers say Amen), though it has been found in tomatoes that have cracked or been injured.

The SWD is similar in size and appearance to those vinegar or fruit flies that come to the bananas in your kitchen. Adult flies are 2-3 mm in length, with red eyes and a tan-colored body with darker bands across the abdomen. Males have characteristic single spots at the leading edge of the tip of the wing and two dark bands made of hairs on their front legs. Females lack wing and leg spots, but are distinguished by a robust, curved, serrated ovipositor (the egg-laying “tail”, visible under magnification). Click here for an excellent identification guide from Pennsylvania State University. For the geekier entomologists and horticulturalists among us, who are interested in a 45-minute lesson on identifying this insect and its damage, see the 2012 webinar by Oregon State University entomologist, Dr. Amy Dreves.

In the backyard, the SWD and its damage is often not noticed until fruit is being harvested. And spraying at this time will not protect the crop, because maggots already are in the fruit.

For more information about this pest, check out some of the many excellent Extension materials listed below. If you find what you suspect to be SWD, follow the instructions on this site for sending specimens in for identification.  The best way to get specimens for identification are with an apple cider vinegar trap.  Note that photos of rotting fruit will likely not be sufficient to identify this pest.  Master Gardeners with an interest in monitoring for this pest in Texas…this would be a great applied research project!

Michigan MSU’s Spotted Wing Drosophila site

Minnesota Spotted wing Drosophila in home gardens

Washington Spotted Wing Drosophila in Western Washington

California Part of the How to Manage Pests series

Oregon Protecting Garden Fruits from Spotted Wing Drosophila and Spottedwing.org

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