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Spotted Wing Drosophila Alert: July 27, 2018

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Click on photos to enlarge.

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

We continue to capture spotted wing drosophila fruit flies in vinegar/yeast traps in raspberry and highbush blueberry plantings this week, but mostly in low numbers. (See table below.) While these counts may indicate that populations are still fairly low in berry fields, growers who have been catching flies in their traps for more than one week and have ripening fruit should put on a protectant spray. We have had reports of raspberry fruit infested with larvae from an unsprayed field.

Spotted Wing Drosophila Larvae in Raspberry

Spotted Wing Drosophila Larvae in Raspberry, photo by David Handley

Male and Female Spotted Wing Drosophila

Male and Female Spotted Wing Drosophila, image by Alan Kenage, Capital Press

Spotted wing drosophila populations are expected to rise in the coming weeks as more ripe fruit becomes available for the flies, especially if conditions remain warm and wet. Set out traps now, if you haven’t already. Start protective sprays on any berries that have begun to ripen when:  more than four spotted wing drosophila flies are caught in a trap, flies are caught consistently for more than one week, or any larvae are noticed in the fruit. Look for fruit flies hovering around fruit and symptoms of premature fruit decay.

Remember to keep waste fruit out of the field as much as possible. Harvest often and regularly to prevent the presence of overripe fruit; and open up the planting to more light by pruning out excess vegetative growth, especially in the lower part of the bush canopy.

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
Penn State University
University of New Hampshire

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 7/20/18 Spotted Wing  Drosophila weekly trap catch 7/27/18
Sanford 13 3
Limington 1 1
Limerick 0 0
Buxton 3 5
Bowdoinham 1 1
Dresden 5 2
Freeport 0 0
Poland Spring 1 0
Mechanic Falls 0 0
Monmouth 3 0
Readfield 0 1
Wales 5
Farmington 8
Fayette 0 0
Wayne 0



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