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Spotted wing Drosophila is now active

The following was slightly edited from an article recently written by Eric Burkness and Suzanne Burkness of the University of Minnesota, Department of Entomology.

The first adult spotted wing Drosophila (SWD) fly of the 2015 growing season was detected in a trap collected on June 23, 2015, in Rosemount, MN (Dakota Co.). Based on this detection, home gardeners with soft-skinned fruit such as June bearing strawberries, summer bearing (floricane) raspberries, and blueberries should begin monitoring their fields, if they haven’t already.

Most June bearing strawberries in Minnesota should be nearing the end of fruiting but summer bearing raspberries and most blueberry varieties should have green fruit and potentially low levels of ripening fruit. Fall bearing (primocane) raspberries and blackberries should not be flowering yet, but these crops will be at increased risk later in the season as the populations of SWD should continue to increase.
Spotted wing Drosophila attacks many types of soft-skinned
fruit, including raspberries, blueberries, and strawberries.
Photo: Jeffrey Hahn, UMN Extension
The first detection of SWD consisted of a single female fly, collected from a Trece Pherocon® SWD trap, baited with apple cider vinegar and a Trece SWD lure (these traps and lures are available through Great Lakes IPM). This detection coincides with previous years where SWD was first found during the last week of June in both 2013 and 2014. It is still unknown if SWD can overwinter in Minnesota or if populations migrate into the state but because this pest reproduces rapidly, monitoring should begin now in all parts of the state.

SWD flies resemble common fruit flies found near overripe fruit, but unlike the common fruit fly, female SWD have the potential to damage otherwise healthy, intact fruit. They will also exploit fruit that has previous damage such as splitting or wounds from birds or disease.

Home gardeners with susceptible fruit are encouraged to monitor their fields regularly to confirm the presence of SWD before considering chemical management options. Although cultural management options are limited, they have been shown to help minimize rapid buildup of SWD populations.

The Department of Entomology and the UMN Extension-IPM Program, in collaboration with the MDA, are monitoring multiple farm locations in the greater metro area and will be posting regular updates regarding SWD phenology and activity on the UMN FruitEdge website.

For more information, see Spotted wing Drosophila in home gardens.