Spotted Wing Drosophila Alert: August 10, 2018

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist; Frank Drummond, Professor of Insect Ecology/Entomology

Captures of spotted wing drosophila (SWD) fruit flies in vinegar/yeast traps in raspberry and highbush blueberry plantings are now increasing in most locations, and at most sites counts rose above threshold levels, including one site with over 200 flies caught. (See table below.) The wet weather predicted for next week may further encourage SWD infestations, as these insects like moisture, and the rain will also lead to more rotten fruit in the field. Most summer-bearing raspberry fields are through or nearly through harvest, but fall fruiting raspberries and blackberries are now ripening and are very susceptible to infestation.  Later ripening blueberries and elderberries are also good hosts for SWD at this time. Growers with these crops should be putting on protective sprays. Pay close attention to product pre-harvest intervals and limits on the number of applications allowed for each product, to develop a management strategy that will be most effective for your situation.

Spotted Wing Drosophila Damage in Elderberry Plant
Spotted Wing Drosophila Damage in Elderberry Plant; photo by David Handley. Click on photo to enlarge.

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

Other IPM Web Pages

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm, P.O. Box 179, 52 US Route 202, Monmouth, ME 04259, 207.933.2100

UMaine Extension Diagnostic Research Lab, Pest Management Unit, 17 Godfrey Drive, Orono, ME 04473, 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 7/27/18
Spotted Wing Drosophila weekly
trap catch 8/3/18
Spotted Wing Drosophila weekly
trap catch 8/10/18
Wells 0 0
Sanford 3 0 5
Limington 1 12 Trap down
Limerick 0 0 7
Buxton 5 0 11
Bowdoinham 1 2 34
Cape Elizabeth 1 18
Dresden 2 5 49
Freeport 0 0 2
Poland Spring 0 0 2
Mechanic Falls 0 0 2
Monmouth 0 2 20
Readfield 1 12 17
Wales 2 216
Farmington 1 0
Fayette 0 0 1
Wayne 0 0