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 numbers increased significantly at all but one of our monitoring sites this week, likely the result of the recent tropical storm and the increased availability of overripe fruit.  Trap counts remain at levels well above those damaging to ripening berry crops (see table below). A five to seven-day spray interval is recommended for ripening berry fields to prevent infestation of larvae in the fruit. This is very likely to remain the case for the remainder of the season, or at least until we have several killing frosts.

Although it can be difficult once harvest has begun, keeping the field free of waste fruit can significantly reduce drosophila numbers. Chill all fruit to 34 degrees F (or as close as possible) immediately after harvest to halt development of any eggs or larvae. If soft fruit and/or larvae are noticed despite a 7-day spray schedule, shifting to a 5 day spray schedule is recommended.


Drosophila Trap
Drosophila Trap, photo by David Handley

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

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 7/31/20 Spotted Wing  Drosophila weekly trap catch 8/7/20 Spotted Wing  Drosophila weekly trap catch 8/14/20
Wells 3 4 36
Sanford 40 135 42
Limington 115 893 1188
Limerick 24 21 114
Cape Elizabeth 121 31 101
Bowdoinham 750 1021 2440
Mechanic Falls 0 11 95
Monmouth 100 61 2944
Wayne 36 661 No data