First spotted wing Drosophila flies of 2014 detected in MSU Extension monitoring network

Spotted wing Drosophila (SWD) traps should be deployed already and growers need to protect ripening or ripe berries against this pest.

Monitoring traps for spotted wing Drosophila (SWD) that were checked during the week of June 15 have revealed the first 2014 activity of this pest in Michigan. These traps were checked the week before and none were found, but over the past week traps placed at the edge of berry crop plantings and in adjacent wild habitat have detected activity of male and female SWD. This timing of first capture is a few weeks later than 2012 and 2013, suggesting that the harsh winter slowed down the spring development of SWD. However, at some of the sites where SWD were trapped, the flies are somewhat more abundant than first captures in previous years.

From a total of 85 traps checked from 23 fields, five male and 21 female SWD were found. The captures were widely distributed across Southwest Michigan from Berrien, Van Buren, Allegan and Ottawa counties. During this first week, SWD have been caught in traps baited with yeast-sugar mix, with the new Trece SWD lures over apple cider vinegar, and also those baited with the Trece lures over soapy water.

With one week of captures, it is difficult to say much about trends in the catches, but this first activity indicates that scouts, crop consultants and growers should be on alert of this pest as their susceptible fruit crops start to ripen. SWD can infest berries only when they are ripening or ripe, so currently ripe strawberry fields and early summer raspberries should be a focus of SWD monitoring and management efforts. A simple salt solution of 1 cup of salt per gallon of water can be used to assess fruit for larval infestation. As blueberries, cherries, and other susceptible crops ripen, growers will need to make management decisions based on fly activity and crop ripeness stage. Information on SWD monitoring and management can be found at MSU’s central website at This site also contains an updated SWD management guide for blueberry growers.

Now that first catches have been made, the Michigan State University Extension fruit team will begin a weekly report on SWD activity from around the state based on the network of traps and sampling of fruit at cooperating farms. These reports will be released on Tuesdays through the summer as part of the MSU Extension Fruit email digests. You can sign up for the Fruit digest for free at the MSU Extension Fruit & Nuts webpage. Look for the envelope icon that says “Sign me up for MSUE News.”

Dr. Isaacs' work is funded in part by MSU's AgBioResearch.

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