Spotted Wing Drosophila Alert — September 11, 2026
David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist; Phil Fanning, Assistant Professor of Agricultural Entomology; Christina Howard, Maine New Farmers Project Manager
Spotted wing drosophila fruit fly numbers in raspberries and highbush blueberries rose further at our monitoring sites this week (see table below). There continues to be a noticeable upward trend in populations at most sites. Larvae have been found in raspberry and highbush blueberry fruit samples collected from most sites, but mostly in plantings that are not presently being sprayed. All ripening fruit should now be protected with regular sprays to prevent infestation. Growers should maintain a 5-day spray schedule on remaining fruit to prevent infestation.
Populations of spotted wing drosophila will continue to increase as more overripe and waste fruit becomes available. Harvest often to reduce the amount of susceptible fruit and check harvested fruit for larvae. Chill harvested fruit immediately to increase shelf life.
For more information on identifying spotted wing drosophila (SWD) and updates on populations around the state, visit UMaine Highmoor Farm’s Spotted Wing Drosophila Alerts webpage.
Other IPM Web Pages
Michigan State University Spotted Wing Drosophila
Penn State University Spotted Wing Drosophila Overview
University of New Hampshire SWD Weekly IPM Reports
David T. Handley
Vegetable and Small Fruit Specialist
Highmoor Farm
P.O. Box 179
Monmouth, ME 04259
207.933.2100
UMaine Extension Diagnostic Research Lab
Pest Management Unit
17 Godfrey Drive
Orono, ME 04473
1.800.287.0279
| Town | SWD weekly trap catch 8/7/2026 | SWD weekly trap catch 8/14/2026 | SWD weekly trap catch 8/21/2026 | SWD weekly trap catch 8/28/2026 | SWD weekly trap catch 9/4/2026 | SWD weekly trap catch 9/11/2026 |
|---|---|---|---|---|---|---|
| Wells | 2 | 5 | 23 | 45 | 582 | 620 |
| Sanford | 14 | 8 | 29 | 127 | 3,024 | 3,232 |
| New Gloucester | 49 | 44 | 12 | 6 | 116 | 483 |
| Cape Elizabeth | 0 | 1 | 6 | 33 | 172 | 2,576 |
| Bowdoinham | 20 | 277 | 489 | 174 | 229 | 139 |
| Monmouth | 3 | 11 | 243 | 16 | 36 | 88 |
| Mechanic Falls | 0 | 1 | 78 raspberry
17 blueberry |
48 raspberry
111 blueberry |
749 raspberry
59 blueberry |
1,125 raspberry
688 blueberry |
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.
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