“We’re trying to be very proactive to get the message out to people,” said Mark Taylor, a health agent in Easton, a town with an alarming number of mosquitoes infected with Eastern equine encephalitis, a rare and potentially deadly illness.

The widespread presence of disease-carrying mosquitoes, also including those with the less serious West Nile virus found in communities west of Boston, is forcing many town governments to act as what one local health agent playfully called “the fun police.”

In the southern suburbs, the locus of human-biting mosquitoes infected with EEE, towns are taking strong measures to protect citizens from the bugs. Public alerts are everywhere. Easton, where EEE-infected mosquitoes were first found on July 8, has canceled or postponed after-dusk children’s races and concerts at Frothingham Park. Canton residents have been told by the local health board to refrain from outdoor activities after 6 p.m., forcing softball teams to call off night games on town fields. Lakeville police are strictly enacting a curfew that shuts down play at town-owned properties at dusk, including at the Ted Williams Camp, a popular spot for baseball, soccer, and volleyball.

Meanwhile, residents in communities west of Boston are receiving official cautionary warnings, but without a similar level of townwide enforcement and negative impact on summertime recreation. Newton’s Health and Human Services Department has warned residents to protect themselves from the West Nile virus while reassuring them the kind of swamps attracting mosquitoes with the more serious EEE do not exist in Newton or its surrounding communities.

Eastern equine encephalitis has been found in a modest sample of bird-biting mosquitoes in Sudbury and Westborough, as well as in Shrewsbury, where the local health board has announced that crews from the Central Mass. Mosquito Control Project will be spraying on Tuesday summer evenings in August.

It is a different story in Easton, where Taylor said the Board of Health is drafting a regulation to ban all nighttime activities that put residents at risk. “We’re not going to ban people from walking down the sidewalk,” he said, explaining the health board is aiming to prevent organized events from subjecting participants to needless exposure after dusk.

“Not everyone gets it. We have people shooting hoops or playing softball at night at the high school,” he said.

Taylor said raising awareness about the public health threat posed by EEE has left him virtually “living, eating, and breathing mosquitoes” for several weeks, his time revolving around updating residents via the town website, social media, telephone, and by posting alerts at outdoor hangouts all over town.

“We are concerned that people have adopted a false sense of security and do not understand the risks,” said Taylor, who is operating in one of four Massachusetts towns, also including Bridgewater, Raynham, and Taunton, with a risk level state health officials raised last week from “high” to “critical.”

About three weeks ago, 21 communities in Southeastern Massachusetts were blanketed with pesticide after mosquitoes in many towns tested positive for the virus, a move that reduced mosquito populations by 60 percent in the areas covered, according to the state Department of Public Health.

Yet officials kept finding more infected mosquitoes, and on Tuesday the state health department announced a second round of aerial spraying to protect six of the most at-risk communities: Bridgewater, Easton, Norton, Raynham, Taunton, and West Bridgewater. The spraying is tentatively scheduled to begin on Monday evening, according to officials.

Two-thirds of the mosquito samples with EEE found since the initial July spraying have been located in these six towns, with 21 of the insect pools found in Easton, the location of Hockomock Swamp, a vast wetlands area and prime breeding ground, according to health officials. Eastern equine encephalitis has also been found this summer in human-biting mosquitoes in Braintree, Canton, Carver, Halifax, Hanover, Kingston, Lakeville, Middleborough, Scituate, and Rehoboth.