Spotted Wing Drosophila Alert and Berry Notes — September 8, 2023

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

SWD Maggot in Raspberry
SWD Maggot in Raspberry; photo by David Handley

Spotted wing drosophila trap counts have remained relatively steady for several weeks, which is unusual for this late in the season.  Past experience has typically shown significant increases in populations late in the season as more food becomes available and more flies come north from southern regions. It may be that there simply isn’t as much food (rotten berries) available yet this season to support the anticipated population explosion. However, numbers are high enough to pose a significant threat to any ripe or ripening berries remaining in the field, so growers should maintain a regular, frequent spray interval to prevent larvae from infesting their fruit.

At this point, a 5-7 day schedule of sprays may be required to minimize fruit infestation in fields.

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

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

UMaine Extension Diagnostic Research Lab
Pest Management Unit
17 Godfrey Drive
Orono, ME 04473

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Weekly Spotted Wing Drosophila Trap Captures

Town Spotted Wing Drosophila weekly trap catch 8/4/23 Spotted Wing Drosophila weekly trap catch 8/11/23 Spotted Wing Drosophila trap catch average for 8/14/23 – 8/25/2023 Spotted Wing Drosophila weekly trap catch 9/1/23 Spotted Wing Drosophila weekly trap catch 9/8/23
Wells 22 166 600 276 740
Limington 2 19 104 65 175
New Gloucester 214 280 840 400 316
Mechanic Falls 20 34 976 1,029 500
Bowdoinham 42 138 624 158 270
Monmouth (unsprayed plot) 43 114 1,408 168 119
Wayne 8 1,012 1,012 696