Spotted wing Drosophila monitoring should be started soon – know what to look for

MSU statewide monitoring program is getting started this week, and urges growers to be able to tell the different between spotted wing Drosophila flies and other Drosophila flies.

Last year in the early 2012 season, the first captures of spotted wing Drosophila (SWD) were found in late May. With this more normal season, Michigan State University Extension has yet to trap SWD in any monitoring traps. Of the many traps already deployed in southwest and northwest Michigan, there have been no catches of SWD as of June 4, 2013. However, traps are catching other small Drosophila flies and it is important that those are not confused with SWD. The photo below is helpful to show the difference between spotted wing Drosophila on the left and another species that has no effect on fruit on the right. Notice that the spotted wing Drosophila on the left has a longer and darker ovipositor, with serrations, highlighted with a green oval.

Example photo of two female Drosophila flies that are (left) and are not
(right) spotted wing Drosophila. The dotted green line indicates the
well-developed and darker serrated ovipositor of the female spotted
wing Drosophila.

Traps should be placed into fields of susceptible fruit crops before they start ripening so growers can be aware of whether the fruit will be at risk of infestation once they ripen. SWD cannot lay eggs into fruit until the fruit start to color, so if this fly has been detected and a susceptible crop is ripening, growers should be initiating their SWD control program.

More information on SWD identification and management is posted at the MSU IPM Spotted Wing Drosophila website. New management guides for blueberry and raspberry will be posted there next week.

Dr. Isaacs' work is funded in part by MSU's AgBioResearch.

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