I’ve seen a few news articles recently lending credence to my hunch that this has been a bumper year for firelfies around Ottawa. I’ve seen many in places that I’m no stranger to, and in way larger numbers than I recall.

Not exactly scientific, but there are other anecdotal reports of high numbers of lightning bugs across social media, and now making the Globe and Mail… I’m going to call it a legit theory.

Fireflies light up the forest
Fireflies light up the forest

So Why So Many Fireflies?

The leading theory among believers is the damp spring we had, which produced an abundance of the fireflies’ favourite food: worms and slugs! Mmmmm.

With no limit on their food intake, populations have been able to flourish, whereas in recent, drier years the general consensus that populations have been down a bit.

Unfortunately there are no official programs running to keep a tab on firefly populations so it’s actually impossible to know for sure.

So… How do Fireflies Glow?

Simple – Magic!

Actually not magic,chemistry. Fireflies produce light in special organs in their abdomens by combining a chemical called luciferin, enzymes called luciferases, oxygen and the fuel for cellular work, ATP. Entomologists think they control their flashing by regulating how much oxygen goes to their light-producing organs.

Fireflies probably originally evolved the ability to light up as a way to ward off predators, but now they mostly use this ability to find mates. Interestingly, not all fireflies produce light; there are several species that are day-flying and apparently rely on the odors of pheromones to find each other.

Each firefly species has its own signaling system. In most North American species, the males fly around at the right height, in the right habitat and at the right time of night for their species, and flash a signal unique to their kind. The females are sitting on the ground or in vegetation, watching for males. When a female sees one making her species’ signal – and doing it well – she flashes back with a species-appropriate flash of her own. Then the two reciprocally signal as the male flies down to her. If everything goes right, they mate.


A few weeks ago I was out in some community gardens with a friend and her daughter – who saw a field of fireflies for her very first time and was truly amazed at how magical nature could be. That’s a win 🙂

[source and source]

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