Click on photos to enlarge

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


Male Spotted Wing Drosophila
Male Spotted Wing Drosophila; photo by Griffin Dill. Actual size: 2-3 mm.

Spotted wing drosophila (SWD) fruit fly numbers remain very high at our monitoring sites this week.  With the ready availability of food (fruit) and no freezing temperatures in the short-range forecast, populations are not likely to decline in the near future.  Populations in all fields remain high above control thresholds, so fruit still 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

Try to keep fields free of waste fruit to reduce their attractiveness to flies. Sort fruit before putting it in storage to remove any soft berries. All fruit should be chilled to 34 degrees Fahrenheit immediately after harvest 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


Other IPM Web Pages
Michigan State University

Penn State University

University of New Hampshire


Spotted Wing Drosophila Larvae in Blueberry
Spotted Wing Drosophila Larvae in Blueberry; photo by David Handley

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 8/21/20 Spotted Wing  Drosophila weekly trap catch 8/28/20 Spotted Wing  Drosophila weekly trap catch 9/4/20
Wells 107 250 303
Sanford 424 1408 1832
Limington 1480 4272 3720
Limerick 594 992 381
Cape Elizabeth 3216 1816 325*
Bowdoinham 2920 1384 1704
Mechanic Falls 351 408 840
Monmouth 2480 3064 1256
Wayne 920 1528 1352

*Trap broken