"To protect against severe economic damage, we've seen farmers spraying more than usual – and this year will probably be no exception," said Shearer. "If farmers use proper sprays at proper times, they should be able to prevent the flies from damaging fruit."

Last year, farmers in the Willamette Valley and Oregon's Mid-Columbia Basin sprayed an average of five to nine times to control spotted wing drosophila at an average cost of $169 an acre, said Walton. Before the fly landed in Oregon, the state's small fruit growers typically sprayed only twice a year to manage other pests, Shearer said. Oregon's blueberry growers alone spent $6 million last year to manage the spotted wing drosophila, Walton estimates.

OSU is also investigating the impact of cold weather on the insect's survival. Early data suggest that some adults can survive fluctuating conditions and can live for 150 days in the winter. Low humidity appears to negatively impact the fly's survival and reproduction, but tests are still ongoing to confirm these findings.

Additionally, OSU researchers have also helped develop an interactive map that estimates the fly's population throughout the U.S. based on temperature and weather conditions. In the mid-Willamette Valley, data suggest that three to five generations of the pest emerge during each growing season.

OSU is also advising growers to monitor for the fly by hanging homemade traps containing apple cider vinegar in plastic cups punctured with small holes that lure in the insect. Amy Dreves, an entomologist with OSU Extension, explains how to make them in the video below.

Researchers are working to develop better baits and traps that catch the spotted wing drosophila earlier in the ripening season to help growers determine when to treat for the pest.

In addition, Bernadine Strik, a berry crops specialist with the OSU Extension Service, is monitoring the presence of the pest in an organic research plot and using organically-approved methods to control the fly.

More information on the fly is on OSU's website at www.spottedwing.org. The site features guides to identify the fly, advice for gardeners and commercial growers, and updates on OSU's research. It also contains links to the following guides published by the OSU Extension Service:

OSU's partners in the spotted wing drosophila project include the Oregon Department of Agriculture, Washington State University and the University of California, Davis. The work is funded by a $5.8 million grant from the USDA.

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