Spotted Wing Drosophila Update – September 2, 2022

Spotted Wing Drosophila on Raspberry
SWD on Raspberry; photo by David Handley.

Spotted Wing Drosophila Alert:  9/2/2022

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology, Christina Howard, New Farmers Program Manager


Spotted wing drosophila fly counts have risen significantly at most locations this week.  All sites were over the recommended control threshold. We anticipate continued growth of fly numbers in the coming days, which will threaten any unprotected soft fruit in the field.


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

All soft-fruited crops, including fall raspberries, blackberries and day neutral strawberries should be sprayed to prevent infestation by spotted wing drosophila larvae. Growers should maintain a 5-7-day spray schedule as long as flies are present, likely until the harvest season is finished.


Keep berry fields clean of over ripe and rotten fruit as much as possible.  Rotten fruit on the plants or on the ground will greatly increase the number of fruit flies present, by providing them with food and egg-laying sites.


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


Other IPM Web Pages
Michigan State University:

Penn State University:



David T. Handley
Vegetable and Small Fruit Specialist


Highmoor Farm                        Pest Management Office
P.O. Box 179                           491 College Avenue
Monmouth, ME 04259              Orono, ME 04473
207.933.2100                           1.800.287.0279


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Town Spotted Wing  Drosophila weekly trap catch 8/19/22 Spotted Wing  Drosophila weekly trap catch 8/26/22 Spotted Wing  Drosophila weekly trap catch 9/2/22
Wells 14 26 647
Springvale 42 142 Crop done
Limerick 290 26 20
New Gloucester 39 32 166
Bowdoinham 24 48 47
Mechanic Falls 26 179 249
Monmouth 76 412 1,519
Fayette 4 43 Crop done
Wayne 15 53 799