Researchers are testing new ways of keeping another spruce budworm outbreak from happening - by stopping the worm's moth from reproducing.

The worms, which can defoliate and kill entire trees, are already wreaking havoc in the Matapedia region of Quebec and scientists are warning it may not be long before they reach New Brunswick.

To stop them, Rosanne Lamb and Glen Forbes with the Canadian Forest Service have set up a 'mating disruption' project in the Acadia Research Forest east of Fredericton.

They've build a cage made from fine mesh that insects can neither enter nor exit, in which they keep a seedling fir tree and a couple of budworm moths.

"In the cage we have strings hanging from the top that at different levels throughout that have a pheromone lure on it," said Forbes.

"The idea is that the pheromone we put in here will confuse the males from finding the females."

Massive deforestation

Forbes said they've set up about 60 of the traps in the forest.

They leave the moth inside the cage for a couple of days, after which they dissect the females to see if they mated with the males.

If they didn't, the pheromones did their job and confused the males enough not to seek out any females.

And if they did mate, the researchers will try again, this time with a stronger dose of pheromones, said Lamb.

Rosanne Lamb,  Canadian Forest Service

Rosanne Lamb with the Canadian Forest Service inspects a moth kept inside the cages. (Philip Drost/CBC)

Spruce budworm caused massive defoliation in the province in the 1970s and '80s, and although their population has been on a downward trend since, scientists started warning of another serious outbreak.

The last time the worms arrived in the province was in 2016 and Lamb said there is a dramatic population increase about every 30 years.

Last year, a Campbellton auto dealership saw millions of the moth arrive in its parking lot overnight. So far this year, the dealership has reported no sightings yet.

"As larvae, they are feeding on the needles [of trees] and year-after-year, after the needles get fed on, time and time again, then over a period of four or five years of heavy feeding it will destroy the tree and kill it," said Lamb.

Trial run traps

Forbes said the traps are a trial run and part of several research projects looking at early intervention strategies.

"There's an existing pheromone out there for spruce budworm that was patented in the 1980s," he said, adding that researchers since discovered new components in the bug's pheromones, which they're now testing.

budworm moth pheromone cage, NB

The researchers build a cage made from fine mesh, in which they keep a seedling fir tree and a couple of budworm moth. (Philip Drost/CBC)

If it works, they plan to patent the five components used to make the lures and "then we would hopefully be able to use it with industry and help protect forests," said Forbes.

"It is a method of controlling populations without killing anything, really," he said. "By preventing mating you control population."

With files from Philip Drost, Information Morning Fredericton