PORTLAND – The browntail moth population continues to collapse along Maine’s southern coast, according to surveys of the insects’ webs.

Surveys in January and February confirm last summer’s observations that the browntail population appeared to be in decline. The survey results are good news in the Casco Bay region, where infestations have caused health problems for several years.

State forest officials surveyed southern Maine woodlands over the winter and found few browntail moth winter nests where they previously had found thousands, said Charlene Donahue, a Maine Forest Service entomologist. Many of the nests were diseased or held parasites.

“Where overwintering webs were once measured in the thousands, they are now measured in the dozens,” Donahue said.

Browntail moths can cause poison ivylike rashes and respiratory problems. The population can grow into the millions during an outbreak and then decline sharply in years when conditions are no longer favorable.

The current decline is the result of recent cold and damp springs, which have weakened the moth’s health and made it more susceptible to disease and parasites.

High numbers of browntails still can be found in parts of Brunswick and Harpswell, Donahue said. Coastal areas of Freeport and the middle of Harpswell have moderate levels of webs, she said, while Yarmouth and Cumberland have low numbers.

The survey revealed few to no webs in Sagadahoc, Lincoln and Kennebec counties.