Here's why fireflies are lighting up London backyards this summer

Kendra Seguin · CBC News

· Posted: Jul 11, 2025 5:00 AM EDT | Last Updated: July 11

Londoners who person noticed their backyards lighting up with tiny flickers this summertime are not alone. 

Some residents and experts alike person reported seeing an summation successful fireflies successful London and its surrounding country this summer, though experts person antithetic ideas connected wherefore this is happening. 

"I've decidedly been seeing a batch much fireflies this season," said Caroline Biel, who leads summertime firefly walks with the Upper Thames River Conservation Authority. 

"Fireflies truly similar moist conditions erstwhile it comes to their larval stage," she said. "This play we haven't needfully seen much rainfall, but I wonderment if the timing of [the rainfall] has been beneficial for them."

In summation to the bedewed spring, Western University biology prof Amanda Moehring said this year's humidity is making a difference for the young insects.

"[The larvae] don't fly, and they really thin to unrecorded successful things similar leafage litter, rotten bogs and moist areas," Moehring said. "Those conditions being humid and damp is truly bully for the larvae."

From the household lampyridae, fireflies are really beetles that are champion known for flashing astatine night, according to Guelph-based entomologist Aaron Fairweather. The insects person 2 compounds wrong their abdomen that, erstwhile combined with oxygen, make a absorption that flashes, Fairweather said.

"It's mostly to find mates, but determination are immoderate exceptions," they said. "There's immoderate weird taxon that person really adapted to paying attraction to the flashing of different fireflies and usage that flashing to lure successful different firefly taxon and devour them."

Fairweather is much skeptical astir the colonisation alteration successful London, adding that determination is nary information astir this year's firefly population, and Londoners mightiness conscionable be heading extracurricular much often. 

"I would accidental radical are paying much attraction to the fireflies that are retired and about. And actually, determination mightiness adjacent beryllium a small spot of a decline," Fairweather said.

Due to situation nonaccomplishment and a emergence successful airy pollution, wide the population is steadily declining crossed Canada, they said. 

Keeping the firefly colonisation healthy

As Londoners get excited astir seeing the flashy insects, Fairweather said it's important for residents to support firefly populations, successful bid for the section situation to thrive.

"One of the ecological reasons fireflies are truly important is due to the fact that of their larvae…They devour things similar worms, slugs, snails, cervid alert larvae and mosquito larvae, and that's a large pest power mechanics successful the environment," they said. "Of course, I deliberation determination is simply a quality successful having fireflies around."

One of the easiest ways radical tin assistance is by turning disconnected outdoor lights astir 8 p.m., Fairweather said.  

"The little airy contamination that we have, the much of a accidental these fireflies person to beryllium capable to spot their woman from crossed the tract and beryllium capable to find a imaginable mate," they said. 

People tin besides see making their yards much firefly friendly, said Moehring, by letting their writer turn longer, keeping a heap of leafage litter successful plot beds and avoiding the usage of pesticides each twelvemonth round.

"The bully happening is that the things we bash to assistance the fireflies besides helps a batch of different things," Moehring said. "It's a bully happening that they're here, flashy and marque america excited astir quality due to the fact that past we marque a bully situation that is bully for tons of organisms."

Where to find airy shows

The champion clip to ticker fireflies successful enactment is astatine dusk, astir 9 p.m. oregon 10 p.m., experts agreed.

If Londoners can't find the insects successful their ain backyards, they tin sojourn adjacent woods, meadows and parks anytime betwixt June and September, they said. 

People tin besides be firefly walks astatine the Fanshawe Conservation Area successful London, Wildwood Conservation Area successful St. Marys and Pittock Conservation Area successful Woodstock, Biel said, for a much guided spotting experience.  

"[Fireflies] decidedly seizure the imagination," Biel said. "Bioluminescence is not that communal successful nature, truthful we're truly fortunate to person them present successful Ontario."

WATCH: More Montrealers are spotting fireflies successful their backyards