Spotted Wing Drosophila
Spotted Wing Drosophila, photo by James Dill

Click on photos to enlarge.

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Christina Howard, Produce Safety Professional


Spotted wing drosophila (SWD) fruit fly counts continue to be very high in our traps around the state this week. The presence of lots of waste fruit and recent warm, humid weather has kept populations high.  Predicted cooler weather may slow activity somewhat, but we know that these flies will continue to infest late ripening fruit until we have had several hard frosts. Thus, any fruit intended for market that remains on the plants needs to be protected. A five to seven-day spray interval is recommended for ripening berry fields to prevent infestation of larvae in the fruit.

Drosophila Trap
Drosophila Trap, photo by David Handley


In addition to insecticide applications, best management practices include: Keep fields free of waste fruit to reduce their attractiveness to flies. Sort fruit before putting it in storage to remove any soft berries. Chill all harvested fruit to 34 degrees Fahrenheit immediately after harvesting to halt development of any eggs or larvae. Rotate pesticide products used regularly to prevent the possible development of resistance.



Current information on registered pesticides for managing SWD is available in the New England Small Fruit Management Guide.  The online version is free and can be viewed here

For more information on identifying spotted wing drosophila (SWD) and updates on populations around the state, visit our SWD blog


Spotted Wing Drosophila Emerging from Fall Raspberries
SWD Emerging from Raspberries 3, Photo by JDill

Other IPM Web Pages
Michigan State University

Penn State University

University of New Hampshire


David T. Handley
Vegetable and Small Fruit Specialist


Highmoor Farm                       Pest Management Unit
P.O. Box 179                            17 Godfrey Drive
Monmouth, ME 04259           Orono, ME 04473
207.933.2100                           1.800.287.0279


Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

The University of Maine is an equal opportunity/affirmative action institution.

Spotted Wing Drosophila Weekly Trap Captures in Yeast/Vinegar traps

Town Spotted Wing  Drosophila weekly trap catch 8/28/20 Spotted Wing  Drosophila weekly trap catch 9/4/20 Spotted Wing  Drosophila weekly trap catch 9/11/20
Wells 250 303 287
Limington 4272 3720 2264
Limerick 992 381 137
Cape Elizabeth 1816 325* 1616
Bowdoinham 1384 1704 776
Mechanic Falls 408 840 1176
Monmouth 3064 1256 1400
Wayne 1528 1352

*Trap broken