Michigan spotted wing Drosophila report for July 15, 2016

Numbers continue to climb throughout the monitoring network; susceptible crops need to be protected.

This is the Michigan State University Extension spotted wing Drosophila (SWD) Statewide Monitoring Network report. Out of the 112 traps collected during the week prior to July 14, 214 females and 169 males for a total of 383 SWD flies were captured from 53 traps, or 47 percent of the traps being monitored. That is a 30 percent increase over last week.

As of this week, SWD adults have been captured in traps baited with commercial lures in strawberry (Berrien, Livingston, Macomb, Ottawa counties), blueberry (Allegan, Berrien, Ottawa and Van Buren counties), raspberry (Allegan, Berrien, Ingham, Kalamazoo, Macomb, Ottawa, Van Buren counties), grape (Benzie, Berrien, Grand Traverse, Leelanau, Van Buren counties), cherry (Allegan, Antrim, Benzie, Berrien, Grand Traverse, Leelanau, Lenawee, Kent, Macomb, Manistee, Monroe, Oceana, Van Buren counties), and peach (Berrien and Kent counties) blocks.

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, and the cumulative total of SWD flies caught in traps by region.


Counties covered in the SWD monitoring network

No. sites*

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:




* Note: not all sites are monitored each week.

** Average is for the week ending July 14, 2016

Average trap catch over the entire network is now over 4 SWD flies per trap in the southern part of the Lower Peninsula and 1 SWD fly per trap in the northwest counties. Traps catching the most flies came from the southwest region, which had an average of more than 7 SWD flies per trap. Some southwest Michigan sites reported more than 30 SWD flies per trap. Ripening fruit throughout the state are likely to be at risk for infestation if not protected. 

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 Lower Peninsula (LP) encompasses all network traps in counties north of and including Clare in the Lower Peninsula (n = 45 traps this week). Southern LP encompasses all network traps in counties south of Clare in the Lower Peninsula (n = 67 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 include strawberry, blueberry, raspberry, grape, tart and sweet cherry, peach and plum. Commercial plantings include 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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