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Weather impacts on spotted-wing drosophila

Eric Burkness, Mary Rogers and Bill Hutchison, Departments of Horticultural Science and Entomology

Spotted wing drosophila flies investigating a raspberry. Photo:Hannah Burrack, North Carolina State University,

In a typical growing season, spotted wing drosophila (SWD) trap catch begins at approximately 755 degree days (DD), using a 50° F base temperature, as the flies begin seeking out and attacking a wide range of wild and cultivated small fruit that begins to ripen in mid to late June. In 2023, we have already surpassed 755 DD at both the Rosemount and St. Paul experiment stations in MN with DDs through June 22nd of 920 and 928, respectively. As of June 22, we still have not detected SWD in either of those trapping locations

Previous research has shown that SWD mating, and egg lay, will be reduced and may cease when temperatures exceed 86° F and as temperatures increase eggs that are laid may not hatch. Despite the adverse weather conditions, SWD infestations could still develop where conditions aren’t as severe, especially in high tunnels or with greenhouse grown fruit crops. Therefore, using a trap on your farm to follow local SWD activity can be extremely valuable in making management decisions, especially as we continue to see significant changes in the environmental conditions during the growing season. For more information on SWD identification, management, and trapping visit

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