researchers working to confirm japanese beetle-killing insect's presence in nova scotia
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japanese beetles are seen along the waterfront trail in dartmouth tuesday july 22, 2025.
tim krochak
/
the chronicle herald
there are some indications of hope in the fight of nova scotia gardeners, farmers, grape growers and property owners against the destructive japanese beetle.
the voracious invasive insect can strip leaves off trees, shrubs and plants in short order, especially if they arrive en masse. there are no real controls in place except picking beetles off leaves and dropping them into soapy water.
because the beetle is invasive, there are no natural predators in nova scotia. but researchers at dalhousie university and agriculture and agri-food canada are trying to determine whether the winsome fly, which is fatal to the beetle, may be showing up in the province.
the fly is also native to japan but has established populations in maine, quebec and ontario, and some have been found in western new brunswick.
it doesn’t kill the beetle directly but lays eggs on its back near the head. once the egg hatches, the larva makes its way into the beetle and starts feeding on tissue. the beetle dies within a few days.
process of confirmation
what researchers are looking at is whether photos that showed up online do indeed show fly eggs on a beetle.
paul abrams, a researcher with agriculture canada, said beetles with a suspected larva found on the south shore were sent to researchers at dalhousie university for testing and then will go to the agriculture canada research centre in kentville.
“it wasn’t possible to tell from the photo on facebook whether it was 100 per cent for sure that they were winsome fly eggs, but the person who posted it did send the actual beetles to a lab at dalhousie,” abrams said.
there have been reports of possible eggs on beetles from other parts of the province as well, he said.
“i did see one other photo that looked good.”
a japanese beetle lounges on the leaf of a plant in a vegetable garden behind a halifax home on friday, aug. 16, 2024.
tim krochak
/
the chronicle herald
the two main ways to confirm whether the beetles are carrying one of the fly eggs is by an extreme close-up photo or dna testing through the kentville research station.
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scientists could also keep the beetle and see if what they’re looking at hatches.
“if they get a winsome fly coming out, that’s the 100 per cent for sure (verification),” abrams said.
“if it confirmed it’s in nova scotia, it may have been there a little while at low levels,” he said. “we do know that it builds pretty slowly at first.”
so what if it’s here?
if the fly is becoming established, it’s good news, abrams said.
“once it’s really well established like it is in the ottawa area and much of quebec, it does look like it’s taking quite a bit off the beetle populations,” he said. “it never gets them down, as far as we know, to really, really low levels, but it’s definitely one of the things that helps keep the population down.”
while there had been talks about whether introducing the fly in nova scotia was an option, that has not happened.
abrams said it’s unlikely the fly spread here on its own from new brunswick because there are no confirmed sightings in that province except for an area along the border with maine.
that means it likely hitched a ride on a beetle or someone or something that was traveling from maine to nova scotia by ferry. the site where the beetle sent to dalhousie was collected from is about an hour away from yarmouth.
abrams said people can help track the spread of the beetle and possibly the winsome fly by downloading and using the inaturalist app to take and post photos.
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