If you grow raspberries, strawberries, cherries, blueberries, or other susceptible soft-skinned fruit, start a trapping program to monitor the potential presence of spotted wing Drosophila (SWD). A single SWD has been detected on June 6 in a trap set on the University of Minnesota St. Paul campus. Last year, the first SWD was trapped on June 27. It is safe to assume that SWD are present throughout the state.
Home gardeners can monitor SWD with homemade traps. Use a large plastic cup with a cover and make several 3/16th inch diameter holes near the top. Put one to two inches of apple cider vinegar into the cup. Add either a yellow sticky card slightly above the vinegar or a little bit of liquid soap, such as dish soap. Hang traps on branches in a shaded location near fruit. Check traps at least once a week, replacing the sticky card (if used) and apple cider vinegar bait. Dispose of the old apple cider vinegar away from the trap location.
Early detection is very important when dealing with SWD as they can rapidly reproduce to large numbers and damage fruit. Management is a three pronged approach, monitoring (trapping), sanitation, and insecticide treatments. For more information about SWD including management, see Spotted wing Drosophila in home gardens.