By Prof. Rowr (with a little help from Brian Roulston)

Rowr! It’s a warm, sticky evening, and the stars are just starting to peek out. Maybe you’re in your backyard or down at Bayfront Park, waiting for the Canada Day fireworks. But as the sky darkens, another magical light show begins in the grass and trees around you: the gentle blinking of fireflies, like tiny living sparklers. These glow‑bugs are one of the most fascinating parts of summer nights, and the science behind their light is a story everyone can enjoy. Fireflies have been around for a long…long time. The oldest fossils of their family are about 99 million years old, meaning they were flashing their lights when dinosaurs still roamed the Earth. Today, there are about 2,000 species worldwide, with 23 confirmed species in Ontario.

The firefly, or “lightning bug,” is one of the most loved insects on the planet. When you see them glowing, it’s a sign that our local environment is still healthy, kind of like a canary in a coal mine. But while they put on a beautiful show for us, fireflies are struggling, and here in Hamilton we have a chance to help keep their lights shining for generations. Rowr… those little sparklers need us.

The Firefly’s Secret: How They Glow  –  Rowr! Listen up, cubs! Ever wonder how a firefly makes its light? It’s one of nature’s coolest tricks. The glow comes from the lower part of their body, in a process called “cold light.” That means they can shine brightly without giving off heat—like a living glow stick. Inside their abdomen, they mix four ingredients: a chemical called luciferin, an enzyme called luciferase, oxygen, and a bit of natural energy. When these mix—flash!—a bright yellow‑green light appears. Rowr! I wish I could make my tail glow like that!

Why Do They Flash?  Fireflies use their glow as a mating signal. Each species has its own flashing pattern—its signature dance move. The males fly around putting on their best light show, while the females wait in the grass and flash back their replies. It’s a glowing dating game out there, and if they miss a signal, it’s a missed connection for the firefly Facebook page. Rowr! Poor fellas.

But the flash has another purpose: protection. Their glow is a blinking “Don’t Eat Me!” sign. If a bird, reptile, or toad takes a bite, the firefly releases a tiny drop of bitter‑tasting blood. The taste is so awful the predator spits it out instantly—and remembers not to try again. It’s not poisonous, just unforgettable. Rowr! Imagine tasting the world’s worst soup and knowing you’ll never order it again. This powerful defense is one reason fireflies have survived for millions of years. Whatever hunted them back in dinosaur times, the trick worked. That same ancient superpower helps them survive today and light up our Hamilton nights.

Home Sweet Home in Hamilton Fireflies need two things to be happy: darkness and moisture. Most of their lives—up to two years—are spent as larvae living in the soil. These little firefly babies hide in damp dirt, under fallen leaves, or inside rotting logs. These spots keep them safe and warm through the winter. As larvae, fireflies are great neighbors. They’re tiny hunters that eat slugs and snails, acting as free, natural pest control for your garden. Rowr! Kind of like little gardeners in glowing pajamas.  When they finally grow up and start flying, adults like tall grass, meadows, and the edges of wooded areas. When the sun goes down, they come out to flash their signals across the night sky.

Why the Lights Are Dimming Fireflies are an indicator species, meaning their presence—or absence—tells us how healthy our environment is. Sadly, firefly populations are dropping worldwide, and parts of Hamilton are also seeing the same trend. Three main things are causing the decline:

1. Too much light Bright streetlights, porch lights, and the glow over cities can drown out firefly flashes. If they can’t see each other, they can’t find mates.

2. Loss of habitat When we pave over wetlands, mow lawns too short, or rake away every leaf, we remove the damp, sheltered places where firefly larvae live for two years.

3. Pesticides Sprays meant to kill weeds, mosquitoes, or other pests also harm fireflies. These chemicals kill the larvae underground and remove the slugs and snails they eat.

How You Can Be a Firefly Hero  Rowr! … and here’s the good news. Fireflies can bounce back quickly if we help them. Hamilton is already taking steps by limiting harmful lawn sprays and protecting green spaces. Here are three simple ways you can help right at home:

1. Turn off the lights If outdoor lights aren’t needed, especially in June and July, turn them off. Darkness helps fireflies find each other.

2. Leave some leaves Don’t rake up every leaf in the fall. Leave a small pile or let the grass grow a little bit longer in one corner of the yard. This creates shelter for larvae to survive winter.

3. Avoid pesticides Try natural pest control methods. This protects firefly babies living in the soil and keeps their food sources alive.

A Canada Day Reminder  This Canada Day, while we enjoy the fireworks and celebrate our natural heritage, let’s remember the tiny wonders glowing in our backyards. Simple actions—reducing outdoor lighting, leaving some natural spaces, and avoiding pesticides—can make a big difference.

Rowr! That’s the science behind those little zappers in your backyard

Happy Canada Day!