Click on photos to enlarge.

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


Drosophila Trap
Drosophila Trap, photo by David Handley

Spotted wing drosophila (SWD) fruit fly numbers continued to increase at nearly all of our monitoring sites this week.  At this time of year, the abundance of ripe fruit available can stimulate SWD populations to increase rapidly.   Most trap counts are at their highest levels of the season, meaning there is high potential of infestation to any ripening berries remaining (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 will probably be required for the rest of the harvest season.


Spotted Wing Drosophila Larvae in Elderberries
Spotted Wing Drosophila Larvae in Elderberries, photo by David Handley

Remember that keeping the field free of waste fruit can reduce drosophila numbers. All fruit should be chilled to 34 degrees F (or as close as possible) 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


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

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






Other IPM Web Pages
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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 8/7/20 Spotted Wing  Drosophila weekly trap catch 8/14/20 Spotted Wing  Drosophila weekly trap catch 8/21/20
Wells 4 36 107
Sanford 135 42 424
Limington 893 1188 1480
Limerick 21 114 594
Cape Elizabeth 31 101 3216
Bowdoinham 1021 2440 2920
Mechanic Falls 11 95 351
Monmouth 61 2944 2480
Wayne 661 No data 920