Spotted wing drosophila numbers are building slowly even though we found an infested red raspberry way back on June 24. The heat and dry weather have most likely kept numbers down.
We did find 6 infested red raspberries out of a 1/2 pint of raspberries purchased in Providence County on 7/20/16.
I haven’t seen any infested blueberries yet this year, but I expect to find some soon. Last year at URI’s East Farm, we found our first infested blueberry on one berry picked 7/20/15. By the 7/28/15 harvest, there were many infested berries. The berries looked fine, but after holding them for 10 days we could see how many were infested when the berries had been harvested. By 8/3/15, the number of infested berries had soared!
If you are going to spray your blueberries, do so right after this heat spell. If you need help choosing an insecticide, see https://ag.umass.edu/sites/ag.umass.edu/files/news/pdf/insecticides_for_small_fruits_for_swd_2016.pdf
Good luck and keep cool!