An infestation of tent caterpillars is on its way.
While there’s no significant tent caterpillar population in the Thunder Bay area this summer a major influx is about a year or two away, said District of Thunder Bay Health Unit entomologist Ken Deacon.
“I saw a couple of tent caterpillars around Thunder Bay last year, which is an indication that they are building up numbers again,” Deacon said.
“There’s no real prediction, however, it won’t be this year, but probably within the next couple of years we should have a net major outbreak.”
Tent caterpillars aren’t considered a major concern until the population explodes during spring, they defoliate trees and cause them major stress.
Deacon said the bugs don’t kill the trees unless the tree is unhealthy, otherwise trees tend to rebound with new leaves rapidly.
In most cases the damage caused by these caterpillars is minimal unless the infestation last for a few years. In those cases tree mortality rates can become substantial.
“We will know when the outbreak begins, and we will know when it’s over,” Deacon said. “There’s a natural parasitoid that follows called the friendly fly.”
The female flies deposit her offspring onto tent caterpillar cocoons. The maggots then move into the cocoons, and feed on them until the developing moth deceases.
After the feeding is completed, the maggots drop to the ground and remain dormant for the winter.
Once the cycle is over both insects disappear for another 10 to 12 years.
Deacon said there is a silver lining as when the caterpillars do arrive they fertilize the ground which helps forest floor plants get an influx of nutrients.
That may hardly be a consolation for the residents who simply find the bugs disgusting.