Spotted Wing Drosophila Update: September 23, 2022

Drosophila Trap
Drosophila Trap, photo by David Handley

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 been remarkably stable for the past few weeks at most sites, but the numbers are still fairly high and pose a threat to any late ripening fruit at this time. Counts are lower in locations where a tight spray schedule is being followed.  We expect that fly numbers will remain high as long as food is available, and the weather conditions are favorable.


A 5-7-day spray schedule is recommended on all soft-fruited crops, including fall raspberries, blackberries, and day-neutral strawberries to prevent infestation by spotted wing drosophila larvae. Sprays should continue as long as flies are present and there is still fruit to harvest.


Spotted Wing Drosophila Larvae in Raspberry
Spotted Wing Drosophila Larvae in Raspberry; photo by David Handley.

Once harvest starts it can be difficult to keep berry fields clean of over-ripe and rotten fruit, but field sanitation has been shown to significantly reduce drosophila numbers, so it pays to keep waste fruit off of the ground as much as possible to reduce food and egg-laying sites.


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


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.


Town Spotted Wing  Drosophila weekly trap catch 9/9/22 Spotted Wing  Drosophila weekly trap catch 9/16/22 Spotted Wing  Drosophila weekly trap catch 9/23/22
Wells 1184 270 214
Limerick 202 34 13
New Gloucester 577 331 227
Bowdoinham 86 224 292
Mechanic Falls 992 623 1,208
Monmouth* 1032 3,088 1,320
Wayne 832 622 721

Weekly spotted wing drosophila trap captures.

*Unsprayed plot