David Owens, Extension Entomologist, owensd@udel.edu
Spotted Wing Drosophila activity usually starts to increase about when blueberries begin to ripen. It is useful to set apple cider vinegar traps for them to time when to start preventative sprays. You can monitor for SWD using apple cider vinegar and putting in a small ball of fermenting wheat dough placed in a deli cup with ¼ inch holes drilled in the side. Alternatively, a tablespoon of active dry yeast, 4 tablespoons of sugar in 12 oz of water can be used, per Michigan State guidance. While you can wait as long as a week to check traps and replace the cider vinegar, the traps will fill up with other insects and other relatively unimportant native drosophila flies. If traps are checked more frequently, it will help with the sorting.
There are numerous insecticides labeled for spotted wing. There’s an excellent article about insecticide management strategies along with efficacy rankings here: https://extension.oregonstate.edu/catalog/pub/em-9360-spotted-wing-drosophila-relative-rankings-seasonal-strategies-insecticide-use. One of the key take-aways from program work over the years is it is better to hit SWD with broad spectrum insecticides first before rotating to more IPM-friendly materials. This is opposite of the usual guidance in other crops.