Adam Prudhomme
Editor
Very hungry caterpillars are chewing their way through treetops across Eastern Ontario, leaving a wave of destruction in their path.
Much liked the beloved children’s book, they have an insatiable appetite and will eat just about anything and everything-but they certainly aren’t adorable. The tiny menaces are known as gypsy moths and Lennox and Addington is among the communities trying to deal with the biggest infestation of them on record.
“There’s no single reason,” David Dutkiewicz, an entomology technician at the Invasive Species Centre in Sault Ste. Marie said of the population increase of the caterpillars. “It’s been a perfect storm of multiple different factors to the reason why they exploded to the levels that they are. Climate has a lot to do with how they got to the stage that they are. Lack of natural predators, all culminates in how these populations explode like that.”
Dutkiewicz says a lack of cold, damp springs in recent years has allowed the species to thrive. Though the species first found its way into Ontario about 50 years ago, the last two years in particular have seen their population swell to problematic levels.
“Throughout Ontario their main host is oak trees,” said Dutkiewicz. “Oak sort of stops just north of Sault Ste. Marie and sort of just cuts right across to north of Sudbury and over to Quebec, north of North Bay. Basically every thing from that line down to Windsor is all oak trees. The gypsy moth population in Ontario has basically reached that area.”
Their appetite, coupled with a very wide-ranging diet, makes them a nuisance.
“These caterpillars are not picky eaters,” said Dutkiewicz. “That is why they can be so destructive. They can eat up to 250 different species of trees, which is mind blowing. Even native species, you might get one insect that goes after 20 or 30 different species. It’s very rare to see one insect go after so many different species. They’re not picky with conifers or deciduous either.”
Finding a solution for property owners with acres of forested land can be tricky.
“There’s a lot individual homeowners can do,” said Dutkiewicz. “It’s more or less landowners that own more than one acre of property, those are the ones that are having real problems right now because they might not be able to afford large scale spray programs like helicopter or aerial spraying. They’re having a lot more trouble.”
A female gypsy moth. Photo by David Dutkiewicz.
Those with just a few trees on their property have a ‘good chance’ at protecting them, he says.
“Right now is a great time where people could be using what’s called a burlap trap method or burlap wrap,” he said. “What you would do is wrap that around the tree and tie it halfway just at chest height and allow the top half to just sort of flop over the bottom half. The caterpillars right now, once they have defoliated the canopy, they’re starting to come down to find shade. A lot of people are finding these caterpillars at the base of their tree. They’re trying to find shade and by providing them a burlap area, you’re basically trapped them by just providing them a place to get out of the sun. What you would do during the middle of the day is just go out, lift up those burlap flaps and just sort of pick off those caterpillars that are under that burlap sack and just put them into a bucket of soapy water.”
Sticky traps on the base of a tree can be effective, but have to be monitored.
“Those measures do work really well but you do have to cautious and monitor those at least once or twice a day to make sure that you don’t get unintentional critters getting caught on it,” said Dutkiewicz. “You can trap things like reptiles or birds. You have to be more vigilant with those sort of traps.”
Another method of prevention can occur in the fall. Property owners can search tree bark or leaves for Gypsy moth eggs, which are tan clumps with the texture of a tennis ball. They can range in size to that of a dime to a toonie. Scraping the eggs into soapy water will prevent the next cycle from starting again in the spring.
Though the caterpillars themselves don’t actually kills trees, they can stress a tree to the point where it becomes more susceptible to disease. Trees that have been stripped of their leaves this year do have a good chance of coming back next year.
As out of control as their population may be this year, there is a bit of hope on the horizon ironically enough in the form of a highly contagious virus known as nuclear polyhedral virus.
“It specifically goes after gypsy moths. It has been found in the population in the last couple of years,” said Dutkiewicz. “Gypsy moth is not very good at social distancing. We’re hoping this sort of virus will just sort of just wipe through and really go after gypsy moth. It has done that in the past where it has collapsed populations. With the virus, the higher the population, the better.”
With the right steps, Dutkiewicz says there’s reason for homeowners and the province as a whole to be optimistic for getting the caterpillar invasion under control.
“We’re not out of the woods, but we’re not into the thick of it where we’re going to see trees dying next year,” he said. “We might see some trees that are definitely struggling.”