Denny's Soapbox

Fireflies, also called lightning bugs are neither bugs nor flies. They are very friendly beetles and most of their families are found east of the Mississippi River. Fireflies are a summer joy, delightful to look at, and fun to catch. Fireflies are about half an inch long with a very soft body. The luminous lower end of a male firefly’s abdomen is yellowish-green, whereas the female has a smaller splotch. It is these ‘taillight’ segments where living light is produced. Eggs, which were secreted in the ground the previous year, may show a touch of luminescence. The hatched juvenile larvae are multi-legged, turtle-like creatures with tiny spots on their underside, softly glowing like view holes in a furnace door. The larvae are big eaters and feed on smaller insects, slugs, snails, and other bug eggs. It’s this stage of the firefly’s life cycle that they are often called “glowworms”.

Why do Fireflies give off Light?

There are several reasons why fireflies blink their lights on summer nights. Flashing is used to locate a mate. The ones that are flying around are males, and the females sit in the brush and respond by flashing their lights. Another reason for the light is to warn predators that fireflies aren’t good to eat. The light on the end of a firefly lets predators know to avoid eating them. The chemicals that make the light are bitter and even the birds don’t like to eat them. A third reason why fireflies light up is to warn other fireflies of danger. The flashing light can be used as a distress signal to alert other fireflies that danger is near. The light produced by fireflies is a unique light. Unique because nearly 100% of the energy given off by the chemical reaction produces light with very little heat.

To most homeowners, the flashes appear to occur randomly across the landscape but fireflies have specific patterns to their light production. There is the call-and-reply interaction occurring between opposite sexes. It is also common to see many fireflies flash in a synchronous fashion from a particular location like a single large shade tree due to the shockwave of a clap of thunder or the explosion of a firework.

There are Firefly Imposters

There are insects that many homeowners believe are fireflies that have had their lights burnt out. You see these during the daytime sitting on plant leaves and flowers. These insects look just like fireflies but they’re not. They are soldier beetles capturing small insects that visit your plants. Soldier beetles are good insects that do not damage any plants in the process of feeding on some of the insects that may cause plant damage. This is Mother Nature’s natural way of getting rid of some damaging insects. This natural process provides a great reason why you should not go out and spray your entire landscape with a pesticide which kills all insects good and bad.