A flicker of hope in the insect world: Firefly, monarch butterfly numbers up, say Ont. researchers

More fireflies are flickering across lawns, parks and campsites in Eastern Canada this summer compared to recent years, says a researcher at Ontario's University of Guelph.

A wet spring created "perfect conditions" for the larvae of the tiny soft-bodied beetles to rebound in 2019, said Aaron Fairweather, an entomologist and PhD candidate.

Firefly larvae are predators and feed on worms, slugs and snails, making them "quite beneficial for us in terms of getting rid of some of those pest species," said Fairweather.

"Because it was so wet, there were a lot more worms and slugs present this spring, and the larvae were able to feed on that, so more of them survived to become adults."

Now, we have "a plethora of them flying around our backyards." 

Fairweather is finishing a PhD under Prof. Nigel Raine, the Rebanks Family Chair in Pollinator Conservation in the university's School of Environmental Sciences.

In tabulating the higher firefly numbers, Fairweather received reports from Montreal, Ottawa and Guelph.

"I've actually noticed it myself."

New generations may not get to 'enjoy the light show'

Fireflies, which produce a chemical reaction inside their bodies that allows them to light up, are a whimsical part of a summer night.

But they've been declining in numbers in recent years worldwide, said Fairweather, who says seeing them rebound this year may lead to conversations about how to conserve their habitats in wetlands.

"It's really too bad because, who knows? Maybe in the next 30 years, for our kids or our kids' kids, they might not have the same opportunity that we do to enjoy the light show that's going on."

There's not much people can do to help fireflies in backyards. They prefer moist soils and wetlands near ponds, bogs, lakes and rivers.

Fireflies are also significantly impacted by light pollution, Fairweather said, as it disrupts their ability to signal for mates.

"It's important that we try and get to know them more, to be able to understand them so we know what our impact exactly is and how we can even better conserve them for the future."

Bump in monarchs too

More monarch butterflies are also fluttering around Canada this year after a strong winter season in Mexico and a wet spring in Texas that saw the butterflies prepare for their flight north, said Gard Otis, an adjunct professor and researcher at the University of Guelph.

In winter 2014, monarch numbers were down significantly in Mexico, with the butterflies only filling about 0.6 hectares of their wintering area. This past winter, butterflies filled about 2.42 hectares.

Otis said about seven per cent of the monarch butterflies in North America come from Ontario, and local conservation efforts help to some degree.

"Every little bit helps."

But Otis warned that butterfly numbers can fluctuate.

This summer, the American snout butterfly has seen an increase, but three common butterflies in Ontario are significantly down in numbers: the cabbage, common sulphur and alfalfa (or orange sulphur) butterflies.

"They're virtually gone. I can count the number of cabbage butterflies on about two hands that I've seen over the last month and normally you'd see dozens, hundreds. And where they went? Nobody knows," Otis said. "And it isn't just here. I've had people in northern Ohio who say the same thing."