Spotted Wing Drosophila Alert — October 2, 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 continue to decline this week (see table below). However, trap counts remain over threshold to prevent infestation at nearly all sites and require regular protective sprays for fruit yet to be harvested. Larvae counts in raspberry and highbush blueberry fruit samples collected were higher this week, but several of the sites are no longer being sprayed and commercial harvest in those sites is over. All ripening fruit remaining should continue to be protected with regular sprays to prevent infestation. Growers should maintain a 5-7-day spray schedule on remaining fruit to prevent infestation.
Cooler night temperatures and shorter daylengths are slowing spotted wing drosophila activity. However, we expect that flies will continue to be active as long as ripening fruit is available, even after frost. Therefore, protection of ripening fruit will be necessary for the remainder of the season.
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 8/21/2026 | SWD weekly trap catch 8/28/2026 | SWD weekly trap catch 9/4/2026 | SWD weekly trap catch 9/11/2026 | SWD weekly trap catch 9/18/2026 | SWD weekly trap catch 9/25/2026 | SWD weekly trap catch 10/2/2026 |
|---|---|---|---|---|---|---|---|
| Wells | 23 | 45 | 582 | 620 | 831 | 314 | 134 |
| Sanford | 29 | 127 | 3,024 | 3,232 | (traps pulled out, crops finished) | – | – |
| New Gloucester | 12 | 6 | 116 | 483 | (traps pulled out, crops finished) | – | – |
| Cape Elizabeth | 6 | 33 | 172 | 2,576 | 2,040 | 677 | 142 |
| Bowdoinham | 489 | 174 | 229 | 139 | 60 | 54 | 49 |
| Monmouth | 243 | 16 | 36 | 88 | 54 | 26 | 3 |
| Mechanic Falls | 78 raspberry
17 blueberry |
48 raspberry
111 blueberry |
749 raspberry
59 blueberry |
1,125 raspberry
688 blueberry |
981 raspberry
594 blueberry |
1,283 raspberry
169 blueberry |
215 raspberry
718 blueberry |
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