The Massachusetts Department of Public Health conducted aerial mosquito spraying in Rochester last weekend after mosquitoes with Eastern Equine Encephalitis were found in the region.

Rochester is one of 21 communities in southeastern Massachusetts that was sprayed.

Karen Walega, Rochester’s Department of Public Health Director, said a notice was sent to residents in advance of the spraying.

Although no mosquitoes with EEE have been found in Rochester yet, Walega said, “We’re really surrounded by it. The time is going to come when they will find a EEE-positive mosquito. The aerial spraying was very necessary. It should have been done earlier.”

A representative from the Massachusetts Department of Public Health said the weekend spraying, which began on Friday night, was the only aerial spraying that will be done this season.

Going forward, Walega said she and her department will continue to remind people to avoid outdoor activity during peak mosquito hours and to use repellent.