Michigan spotted wing Drosophila report for Aug. 12, 2016

Traps continue to catch high numbers of spotted wing Drosophila flies. As high risk of infestation continues to be expected, susceptible crops must be protected.

This is the Michigan State University Extension spotted wing Drosophila (SWD) Statewide Monitoring Network report. Trapping continues in fruit plantings that have yet to be harvested, including blueberry, grape, peach and raspberry sites. Out of the 78 traps collected during the week prior to Aug. 11, we captured a total of 2,605 female and 2,385 male SWD for a total of 4,990 SWD flies. We found SWD in 100 percent of the traps being monitored this week, indicating that SWD is active now in all locations around fruit farms.

Average SWD catch in traps being monitored this week was less than 60 SWD flies per trap in the southern part of the Lower Peninsula and almost 80 SWD flies in the northern part of the Lower Peninsula. Ripening fruit throughout the state continue to be at high risk for infestation if not protected.

Some growers are having a hard time controlling SWD at this time. It is important to maintain short application intervals and to reapply after rain events – be sure to check product labels for reapplication restrictions and season maximums. Check with your local Extension staff or crop consultants and refer to the “2016 Fruit Management Guide” for recommendations for your crop.

Table 1. The regions that are being monitored for SWD in 2016, how each region is defined (by the counties listed), the number of sites in each region that were monitored this week, the cumulative total of SWD flies caught in traps by region and the average number of SWD flies caught per trap.


Counties covered in the SWD monitoring network

No. sites this week

Cumulative SWD Total

Avg SWD flies per trap*


Genesee, Ingham, Lenawee, Livingston, Macomb, Monroe, Oakland





Allegan, Berrien, Kalamazoo, Ottawa, Van Buren





Ionia, Kent, Muskegon





Mecosta, Oceana





Antrim, Benzie, Grand Traverse, Leelanau, Manistee




Grand Total:




* Average is for the week ending Aug. 11, 2016.

Northern LP bar graph

Southern LP bar graph

All sites bar graph

Bars represent the average number of SWD flies caught in monitoring network traps each week. Dots represent the percent traps that captured SWD that week. The shaded bar across each graph represents the proposed threshold for triggering management of the pest in susceptible crops. Northern L.P. encompasses all network traps in counties north of and including Clare in the Lower Peninsula (n = 20 traps this week). Southern L.P. encompasses all network traps in counties south of Clare in the Lower Peninsula (n = 58 traps this week).

Traps in the network are baited with commercially available lures and placed in susceptible crop fields or orchards, or in a location adjacent to susceptible crops, in areas where SWD infestation has been recorded in the past. Commercial plantings included strawberry, blueberry, raspberry, grape, tart and sweet cherry, peach and plum. Counties included in the 2016 trapping network are Allegan, Antrim, Benzie, Berrien, Genesee, Grand Traverse, Ingham, Ionia, Kalamazoo, Kent, Leelanau, Lenawee, Livingston, Macomb, Manistee, Mecosta, Monroe, Muskegon, Oakland, Oceana, Ottawa and Van Buren.

For the most current recommendations for monitoring this pest, please refer to “Monitoring traps for catching spotted wing Drosophila.” You can find out more about how to identify and manage this pest in fruit crops by visiting MSU’s Spotted Wing Drosophila website.

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