Moncton's mosquito infestation may not abate until November, a biologist says. (Dave Chidley/Canadian Press)

Moncton residents are busy slapping and scratching as the city copes with about 10 times the normal number of mosquitoes buzzing around.

Plenty of rain and warm weather helped build them up during the summer months, said Louis LaPierre, a biology professor at Moncton University and general director of the Greater Moncton Pest Control Commission.

And now a more aggressive fall breed has moved in, he said.

"They need only a very short time to get their meal of blood, so they are aggressive," LaPierre said. "They've been here every year, but not in the numbers we've seen this year."

A count in June showed 55 million mosquitoes, and the number has continued to climb, LaPierre said.

"It has been the perfect storm for bugs this year," he said, citing continuous rain in June and July and abnormally high rainfall in August — more than 300 millimetres, compared with the average 92 millimeters.

Moncton's pest control program has wrapped up for the year, so there's nothing to curtail the mosquitoes, LaPierre said.

It will take an extended period of cold weather to get rid of them. "Frost doesn't really get rid of them. It's really got to be a sustained cold for them to slow down," he said.

"The water temperature's got to move down to three or four degrees and stay there. Water temperatures are still right up there — 10, 11, 12 degrees."

It will likely be November before the mosquitoes are completely gone, LaPierre said.