As growers are on the lookout for spotted wing drosophila (SWD) this spring and summer, they should be prepared to identify larvae and to distinguish them from other insects that might be present in fruit. Last year I developed two two “do-it-yourself” posts on telling SWD larvae apart from other common critters in strawberries and blueberries.
Now is a good time to brush up on post harvest SWD sampling in general, which I describe in this factsheet.
Regardless of what fruit you’re sampling, the most important step to correctly identifying SWD is what fruit you sample! SWD prefer sound, marketable fruit. If you sample overripe, rotten, or otherwise damaged fruit, you are likely find native, non SWD drososphilids in addition to lots of other critters. These “cousins” of SWD feed on rotting fruit, and we cannot tell native drosophila from SWD as larvae. Therefore, it is extremely important that only sound fruit be sampled; otherwise, you may assume you have SWD when they are not present.