Caterpillars invade Great Slave Lake area

Some places around Great Slave Lake now look like the set of a horror film about caterpillars taking over the world.

Northern tent caterpillars are chewing the leaves of willow, wild rose and other plants in the North Slave, and forest tent caterpillars are mowing through the leaves of aspen in the South Slave.

• Southern N.W.T. tent caterpillar invasion part of natural cycle

• Swarms of tent caterpillars spotted on Saskatchewan trees

It is the third year in a row for a caterpillar infestation, according to Jakub Olesinski, a forest ecologist with the Department of Environment and Natural Resources. But this is the first year they have taken a liking to the territorial capital.

"We have never had an outbreak of northern tent caterpillars in Yellowknife before," Olesinski said.

"So this is the first of its kind that we're seeing there and it's very interesting that it's going for its third consecutive year."

Olesinski says caterpillars, like many species, have a boom and bust cycle. In the south it's typically a boom year every 12 years. In the N.W.T.,because of the colder climate, it's every 20 years.

Trees will be OK

Olesinski says aerial surveys show that the caterpillars in the South Slave ravaged 100,000 hectares of aspen last year.

Though some trees are almost completely denuded of leaves, the caterpillars are not fatal.

"There is no significant damage to trees even if they are defoliated completely they are able to re-grow the leaves later in the season," said Olesinski.

"So as bad as it looks right now, those trees will be back in form in about four weeks."

He says the plants the caterpillars in the North Slave feast on also recover after the pests cocoon next month to begin their transformation into moths.

There is not much historical data about caterpillar infestations in the Northwest Territories, says Olesinski, so it's difficult to say if climate change is driving it.

"We see some signs of shifts in pest ranges and forest tent caterpillars is one example of such shifts, but we're not certain this is the cause, but it could be a contributing factor, for sure."