Hydrangea Black Flies
I have Quick Fire Hydrangeas. The last couple years they attracted big black ugly flies. This year they are swarming with what looks like house flies. If the flowers were not against my house, I would ignore it but it's a serious nuisance because of their location. Any suggestions? Thanks kindly for your help. Mary Erickson St. Paul
Ramsey County Minnesota
Thank you for the question. It's hard to say what insect is swarming your hydrangeas and this needs to be figured out before a solution can be suggested. They could be pollinators (some resemble flies and some are flies) or you could have an insect pest potentially harming your shrubs. In order for us to answer your question, please provide more information. Do your hydrangeas seem healthy and are they are growing well? Look closely at the stems and both sides of the leaves. How about sending us a photo of the insect?
If the insects are pollinators, they will eventually move on. The only way to rid yourself of them before their job is done is to remove the blooms. If they are pests that are harming your shrubs, we need to identify them before treatment is suggested.
Thank you for contacting Extension.