Winnipeg is starting to see an infestation of forest tent caterpillars, the fuzzy black critters that devour leaves on trees until the branches are bare.

A new cycle of the insects started in the city last summer, and now the larvae are eating leaves from trees mainly in Transcona and Sage Creek, according to the City of Winnipeg.

Charlene Lemoine has already noticed them in her Island Lakes neighbourhood.

Tent caterpillars

A cluster of tent caterpillars clings to a tree in Winnipeg's Island Lakes neighbourhood. (Deanna Williamson/CBC)

"Some of my friends — they have lots of them in their yard. I know some of them are like crawling up the house and all over their trees and stuff," she said.

"We started noticing some forest tent caterpillars kind of scattered here and there through the city in really small quantities last year, and this year we're starting to see the numbers increase," city forester Martha Barwinsky told CBC News.

Forest tent caterpillar infestations happen in Winnipeg about every 12 to 15 years, said Barwinsky, adding that the last outbreak took place in 2000.

"What we'll see this year with the trees, we're seeing it right now, where there will be some trees in certain areas that will be completely defoliated," she said.

Barwinsky said it's difficult to know how severe the latest infestation will be.

She is recommending that homeowners spray infected trees with the biological insecticide Bacillus thuringiensis subspecies kurstaki (BTK).

"They are big eaters. They will defoliate a tree in large numbers," said Barwinsky.


Forest tent caterpillars can defoliate trees quickly as they feast on stands of deciduous trees. (CBC)

A tent caterpillar infestation has also hit the northern Ontario town of Red Lake, with trees there stripped bare and vehicles covered with the insects and their feces.

Some areas of Manitoba have also seen infestations this year.

"We are getting reports from my colleagues in the province that north-western and western Manitoba are hit quite hard right now, so we are expecting numbers [here] to build up  in the next year or two," said Barwinsky.