By Kay Lazar Globe Staff

One day after public health officials announced they will spray a wide swath of southeastern Massachusetts with pesticides to combat disease-carrying mosquitoes, more infected insects have been found, prompting a decision to substantially widen the targeted area to nearly two dozen communities.

Aerial spraying is slated to begin Friday evening and continue Saturday night to prevent the spread of eastern equine encephalitis to people in 21 cities and towns.

Mosquitoes infected with EEE were found in Rehoboth, prompting officials to urge residents there to avoid nighttime activities, when the insects are most active. The state Department of Public Health said the EEE threat level has been raised to “high” in Rehoboth and to “moderate” in neighboring Attleboro, Seekonk, and Swansea.

Here is the announcement from state health officials:

The Massachusetts Department of Public Health (DPH) today announced that an additional ten communities in southeastern Massachusetts will receive aerial spraying of pesticides against mosquitoes, bringing the total number of communities in the spraying zone to 21. Spraying is scheduled to begin on the evening of Friday, July 20 after dark, and will continue on the evening of Saturday, July 21, weather permitting.

The list of communities that will be sprayed include: Acushnet, Berkley, Bridgewater, Carver, Dighton, East Bridgewater, Easton, Freetown, Halifax, Hanson, Kingston, Lakeville, Middleborough, Norton, Pembroke, Plympton, Raynham, Rehoboth, Rochester, Taunton, and West Bridgewater. Residents are encouraged to check the DPH website at www.mass.gov/dph for updates.