Region of Waterloo will not spray against gypsy moth caterpillars this year

It will be up to homeowners to protect trees from gypsy moth caterpillars this year, as the Region of Waterloo says it will not be taking preventative — or reactionary — measures against the hungry insects in 2021.

The region says there is minimal spread of the caterpillars in the urban areas; in 2020 much of the deforestation happened in rural areas the townships including North Dumfries.

Trees that are normally impacted by the gypsy moth caterpillars are maple trees, oak trees, birch trees, aspen trees and softwood trees such as white pine according to Chris MacQuarrie, research scientist at Great Lakes Foresting Centre.

"The Ontario Ministry of Natural Resources and Forestry does a survey every year to see what insects are causing problems," MacQuarrie told CBC News. He said deforestation from gypsy moths went from 47,000 hectares in 2019 to 580,000 hectares in 2020. 

"That's about a 1200 per cent increase in defoliation, and there's certainly some parts of Ontario they're predicting are going to be pretty bad this year."

Municipalities can spend a lot of money to preventatively spray trees that are appetizing to gypsy moth caterpillars.

The City of Hamilton had a plan to spend up to $2.5 million — $955 per hectare — to drop a pesticide called BTK from the sky in 2017. 

Spraying for caterpillars 'hit and miss'

Albert Hovingh, a forester and an environmental planner for the Region of Waterloo, says it's more cost-effective to treat large areas and forestry cities like London, Ont., compared to a smaller area such as a park, because of the volume of amount of tree canopy. 

"Because of the way [the infestation] is spread out and it's sort of in pockets, it's not really having a big impact — or it didn't last year — on the urban areas."

"It also depends on what kind of trees you have in the forest canopy," he said. "They tend to prefer certain species so cities that have a lot of oaks, that's why Oakville and Burlington are quite concerned because they have a lot of oak trees."

Hovingh said the spraying for gypsy moth caterpillars isn't a guaranteed solution, either.

"You also have to get your timing right with the spraying," said Hovingh. "You have to do it twice. The insecticide is sprayed on the foliage, it sits on the leaves and the insects eat the leaves. So because it's sitting up on the foliage if you get rain, it washes off." 

"So it's a kind of hit and miss with that."

Options for property owners

Residents who are concerned about infestation on their properties can get their trees sprayed themselves. 

The Township of North Dumfires published an online resource for with information for homeowners on how to wrap trees in burlap, set pheromone traps and destroy egg masses in the coming fall months.  

The Township's chief administrative officer Andrew McNeely also told CBC K-W in an email that it will will also deploy techniques similar to what is described on the webpage.