Drosophila Trap
Drosophila Trap, photo by David Handley



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




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

As we finish out the fall berry season, spotted wing drosophila (SWD) fruit fly counts were mostly higher this week, including a season record of over 8,000 flies in one southern trap.  Most farms have now ended their berry harvests, although there are still fall raspberries and strawberries available at some locations.  We intend to pull out our traps from all the monitoring sites next week. So, the next issue of this Alert will be the last for the season.  For those farms still harvesting fruit, populations remain high enough to cause significant infestation of any remaining berries.  A five to seven-day spray interval is recommended for any remaining fruit to prevent infestation of larvae.


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


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 9/25/20 Spotted Wing  Drosophila weekly trap catch 10/2/20 Spotted Wing  Drosophila weekly trap catch 10/9/20
Wells 73 69 42
Limington 907 1808 8296
Limerick 51 40 147
Bowdoinham 1520 356 1032
Mechanic Falls 45 87 1144
Monmouth 416 253 490
Wayne 5548 262 1360