Fireflies are threatened, but you can help them. Here’s how

Fireflies in the forest Photo by WUT.ANUNAI/Shutterstock

While swarms of insects rarely provoke feelings of adoration, the glow of fireflies on a summer night at the cottage is a magical sight. The bioluminescent lights produced by these charismatic insects are a draw for cottage-goers and tourists alike. Their universal appeal makes them a culturally and economically important group of insects. A study led by Sara Lewis, a professor in evolutionary and behavioural ecology at Tufts University in Massachusetts, has sounded the alarm about the future of fireflies. The study identifies several global threats to the insects, including habitat loss, light pollution, and pesticides.

Fireflies in Ontario face the same challenges identified in Lewis’s study. In a rapidly urbanizing Southern Ontario, action must be taken to ensure that they will continue to light up the night sky.

Fireflies aren’t important just because they provide cottagers with a free light show. They also make good neighbours, by keeping populations of nuisance species in check, says Aaron Fairweather, a Ph.D. candidate in environmental sciences at the University of Guelph. Firefly larvae are heavy predators of mosquito larvae, blackfly larvae, slugs, and worms, says Fairweather.

Despite their significance culturally and ecologically, Fairweather says that there “really has been a sheer lack of research on fireflies in Ontario.” A review co-authored by Stephen Marshall from the University of Guelph concluded that there are probably about 23 species in Eastern Canada, most of which could be found in Ontario, says Fairweather. But without an active search for fireflies in new locations, we don’t know for sure how many species call Ontario home.

Firefly larvae need wet habitat to survive, so the insects often end up vying for the same lakeside habitats where people vacation. “These are beautiful areas for us in terms of camping and cottaging,” says Fairweather. “But if we are urbanizing them or renovating them to create our cottage homes and to create spaces where we can camp, we’re removing some of that habitat which the fireflies are relying upon.”

More people in these environments also means more artificial lights. Light pollution prevents fireflies from finding mates and communicating with one another, says Fairweather.

Cottagers can make some easy changes to create a firefly-friendly environment. For one, “you don’t want to transform your whole property into a lawn,” says Fairweather. Also, leave natural plants of different heights on your property. This will not only provide fireflies with a home, but it also creates a display platform that fireflies can use for their bioluminescent shows. And to combat light pollution, simply turn off lights when leaving a room, and switch off outdoor patio lights when they’re not needed.

But to truly help fireflies, more research is needed to understand the biology of these animals and the impact humans have on them. “One figure that shocked me,” says Fairweather, “was the fact that there has only been two [scientific] papers in total talking about fireflies and pesticide use.”

On a hopeful note, Fairweather received dozens of emails over the last season from people saying they were seeing abundant numbers of fireflies. “Last year was the perfect conditions for fireflies,” says Fairweather. A wet fall, a mild winter, and then a wet spring created more habitat for firefly larvae and an increase in their food sources of mosquito larvae and slugs.

Fireflies have been lighting up cottage country

If you enjoy watching fireflies at your home or cottage, you can help scientists by participating in Firefly Watch, a citizen science project collecting sightings from all over North America. Learn more about the program at Firefly Watch.

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