Why and how do lightning bugs light up?

No matter if you call them lightning bugs or fireflies we all remember as a child catching these bugs in our hands, putting them in a jar, or just sitting on the porch on Summer nights watching them light up the yard. When you really sit back and think about it, you may wonder...how in the world does a bug just create light from its body? Why do they do it?

How

Lightning bugs or fireflies light up at night by producing a chemical reaction inside of their bodies. This type of light production is called bioluminescence. This chemical reaction is caused by a chemical compound in their abdomens called luciferin. Air goes into the lightning bugs abdomen and reacts with the luciferin, producing the bioluminescent light that we see from the bugs.

Why

There are a couple reasons thought to be behind why lightning bugs or fireflies do this in the first place. The first, as many would guess, is for their safety and protection. Fireflies produce defensive steroids in their bodies that make them unappetizing to predators. Larvae use their glows as warning displays to communicate their distastefulness. Sometimes you will notice however that frogs really aren't fooled by the light as frogs eat fireflies all the time, sometimes to the point where they will begin to light up themselves.

This still isn't the only reason why lightning bugs light up. The other reason is for romance. The male fireflies light up to signal toward the female fireflies. Some females will even mimic other species of fireflies' flashing. However, that isn't all that some female fireflies do. Female fireflies in the genus Photuris mimic the flash of females in the genus Photinus attracting Photinus males, which they lure in to eat.

Lightning bug population decline

You may have noticed that seeing lightning bugs might not be as common as they used to be when you were a kid or even just a few years ago. Humans are ones to blame for the decline in lightning bug/firefly populatoins mainly because of light pollution. This, development of fireflies’ habitats, and harvesting are all leading to a decrease in the number of fireflies.