The box tree moth could wreak havoc on your shrubs. Here's what you need to know

If you have boxwood plants in your yard or neigh‐ bourhood, there's an inva‐ sive pest you need to be on the lookout for this spring.

The box tree moth is an invasive species that can dec‐ imate boxwood plants - going from larvae to caterpillar de‐ vouring the plant, only to turn into a moth, fly away and continue the cycle.

The Canadian government issued a warning last week about the pest, and some common remedies for them are in short supply in cities like Windsor, Ont.

"The good thing is that the pests only feed on box‐ wood, so there's no chance it'll run through all of your landscaping," said Sandy MacDonald, a horticulture professor at St. Clair College.

"We are undergoing a very serious problem with our boxwood plants and that encompasses all boxwood, all different varieties of box‐ wood."

WATCH: What home gar‐ deners need to know about the box tree moth:

This year's box tree moth season started early, Mac‐ Donald said, because of the warm weather in the region. We can also expect to see a second generation of box tree moths in July or August, and some can even overwin‐ ter, he says.

At first, he said the insect may be smaller and there will be some patterning on leaves. But as the caterpillars grow, they can decimate the boxwood's foliage and even small branches.

"There's not a really good substitute for boxwood. We've planted it extremely extensively in our landscapes throughout our province. There are literally millions of them," MacDonald said.

"I think this is something that we're going to expect to deal with now for a good decade at least."

Box tree moth poses a threat to landscape in‐ dustry

The box tree moth, an inva‐ sive species, was found for the first time in North Amer‐ ica in Toronto.

Today, it's confined mostly between Windsor and Toron‐ to and the Niagara region. However, last year the box tree moth was found in Que‐ bec, Nova Scotia and New Brunswick.

Colin Cassin is a policy manager with the Invasive Species Council.

"So there's some consid‐ erable economic interests at stake here, because the those caterpillars are vora‐ cious insects, voracious eaters, and they do cause plant mortality or kill the box trees as they find them," Cas‐ sin said.

"They've been widely used for many, many decades in terms of their use in the landscape. People are used to seeing them, people are used to requesting them and they are grown here in On‐ tario and they're exported ... it does pose a threat to that sector, to that industry."

Janine West is the grower technical analyst with Land‐ scape Ontario. She says the impact of the pest has "actu‐ ally been quite devastating" for the nursery sector.

"There's been a significant loss of sales and the ability to ship to the U.S. has been af‐ fected," she said.

"There's a ban on ship‐ ping boxwood from Ontario from infested areas into the U.S. and so that has been a major hit as as we had a very large and healthy export market for boxwood plants."

Some possible remedies for home gardeners

If you have boxwood shrubs in your garden and want to keep the pests at bay, there are a few things you can do, MacDonald says.

The first thing is to start taking a close look at your boxwood plants, even if they appear healthy.

"Just sort of pry it open a bit and to check inside for a kind of white webbing that might be one of the first things you would see."

Unfortunately, there's no preventative measures gar‐ deners can take. But there are a number of remedies once you have the box tree moth, he added.

The first thing MacDonald says gardeners can explore are nematodes, a "small worm-like creature" that are environmentally friendly and non-toxic.

But he cautioned they have to be applied throughout the plant and at the end of the day to work.

"Secondly, which is proba‐ bly the most popular one now and which is also be‐ coming very much in short supply, is a product called BTK ... this is a natural occur‐ ring bacteria that can be found in soils and it will de‐ stroy the pest from the inside out."

Finally, MacDonald says there's pyrethrin spray, a botanical insecticide.

"It actually will destroy the larvae very quickly. In fact, usually within one hour they are falling right off the plant," he said. "This can have some environmental side effects, but it still is a very, very safe product."