Here's why fireflies are lighting up London backyards this summer
Homeowners can help the firefly population by reducing light pollution and growing longer grass
Londoners who have noticed their backyards lighting up with tiny flickers this summer are not alone.
Some residents and experts alike have reported seeing an increase in fireflies in London and its surrounding area this summer, though experts have different ideas on why this is happening.
"I've definitely been seeing a lot more fireflies this season," said Caroline Biel, who leads summertime firefly walks with the Upper Thames River Conservation Authority.
"Fireflies really like moist conditions when it comes to their larval stage," she said. "This season we haven't necessarily seen more rainfall, but I wonder if the timing of [the rainfall] has been beneficial for them."
In addition to the wet spring, Western University biology professor Amanda Moehring said this year's humidity is making a difference for the young insects.
"[The larvae] don't fly, and they actually tend to live in things like leaf litter, rotten bogs and moist areas," Moehring said. "Those conditions being humid and damp is really good for the larvae."
From the family lampyridae, fireflies are actually beetles that are best known for flashing at night, according to Guelph-based entomologist Aaron Fairweather. The insects have two compounds inside their abdomen that, when combined with oxygen, create a reaction that flashes, Fairweather said.
"It's mostly to find mates, but there are some exceptions," they said. "There's some weird species that have actually adapted to paying attention to the flashing of other fireflies and use that flashing to lure in other firefly species and eat them."
Fairweather is more skeptical about the population change in London, adding that there is no data about this year's firefly population, and Londoners might just be heading outside more often.
"I would say people are paying more attention to the fireflies that are out and about. And actually, there might even be a little bit of a decline," Fairweather said.
Due to habitat loss and a rise in light pollution, overall the population is steadily declining across Canada, they said.
Keeping the firefly population healthy
As Londoners get excited about seeing the flashy insects, Fairweather said it's important for residents to protect firefly populations, in order for the local environment to thrive.
"One of the ecological reasons fireflies are really important is because of their larvae…They eat things like worms, slugs, snails, deer fly larvae and mosquito larvae, and that's a big pest control mechanism in the environment," they said. "Of course, I think there is a beauty in having fireflies around."
One of the easiest ways people can help is by turning off outdoor lights around 8 p.m., Fairweather said.
"The less light pollution that we have, the more of a chance these fireflies have to be able to see their girlfriend from across the field and be able to find a potential mate," they said.
People can also consider making their yards more firefly friendly, said Moehring, by letting their grass grow longer, keeping a pile of leaf litter in garden beds and avoiding the use of pesticides all year round.
"The nice thing is that the things we do to help the fireflies also helps a lot of other things," Moehring said. "It's a good thing that they're here, flashy and make us excited about nature because then we make a good habitat that is good for lots of organisms."
Where to find light shows
The best time to watch fireflies in action is at dusk, around 9 p.m. or 10 p.m., experts agreed.
If Londoners can't find the insects in their own backyards, they can visit nearby woods, meadows and parks anytime between June and September, they said.
People can also attend firefly walks at the Fanshawe Conservation Area in London, Wildwood Conservation Area in St. Marys and Pittock Conservation Area in Woodstock, Biel said, for a more guided spotting experience.
"[Fireflies] definitely capture the imagination," Biel said. "Bioluminescence is not that common in nature, so we're really lucky to have them here in Ontario."
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