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 counts were lower at all but one of the remaining monitoring sites this week. This is likely due to the cooler temperatures, frosts and shorter day lengths we’re currently experiencing. However, populations are still high enough at all locations to cause significant infestation of any remaining berries in the field.   Any fruit remaining for harvest 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.



In addition to insecticide applications, best management practices include

  1. Keep fields free of waste fruit to reduce their attractiveness to flies.
  2. Sort fruit before putting it in storage to remove any soft berries.
  3. Chill all harvested fruit to 34 degrees Fahrenheit immediately after harvesting to halt development of any eggs or larvae.
  4. 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




SWD Maggot in Raspberry
SWD Maggot in Raspberry; photo by David Handley

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

Spotted Wing Drosophila Larva in Blackberry
SWD Larvae in Blackberry, photo by David Handley








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 9/11/20 Spotted Wing  Drosophila weekly trap catch 9/18/20 Spotted Wing  Drosophila weekly trap catch 9/25/20
Wells 287 149 73
Limington 2264 1968 907
Limerick 137 98 51
Cape Elizabeth 1616 418 *
Bowdoinham 776 2144 1520
Mechanic Falls 1176 1104 45
Monmouth 1400 1000 416
Wayne 1584 2976 5548

*Trap pulled out, crop done