Spotted Wing Drosophila Update: August 26, 2022

Spotted Wing Drosophila
Spotted Wing Drosophila, photo by Griffin Dill

Spotted Wing Drosophila Alert:  8/26/2022

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology

Spotted wing drosophila fly counts were over the recommended control threshold at all of our scouting locations this week. Numbers at some sites have risen but most have remained relatively stable.  At these levels, the flies should be controlled with regular sprays. We still anticipate exponential growth of fly numbers in the coming days.

All soft-fruited crops, including fall raspberries, blackberries, and day-neutral strawberries that are now being harvested need to be protected. Growers should maintain a 5-7-day spray schedule once fly numbers have exceeded the threshold of 6 SWD flies in a trap per week, or larvae are noticed in the fruit. Look for fruit flies hovering around fruit and symptoms of premature fruit decay.

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 8/12/22 Spotted Wing  Drosophila weekly trap catch 8/19/22 Spotted Wing  Drosophila weekly trap catch 8/26/22
Wells 13 14 26
Springvale 5 42 142
Limerick 11 290 26
New Gloucester 84 39 32
Bowdoinham 574 24 48
Mechanic Falls 0 26 179
Monmouth 23 76 412
Fayette 3 4 43
Wayne 6 15 53