Denny's Soapbox

You Light Up My Life

I received the following email on July 6th and I’d like to share

Dear Denny,

Last night my family and I witnessed an amazing sight in our Deerfield township backyard. Thousands of fireflies were in one of our large trees and they began blinking simultaneously. They looked like Christmas lights. We always thought the males flew to the ground to the awaiting females, so I looked it up on the internet today and an article on the Colorado state University website said this, ‘firefly tree’ is rare in ‘The New World’. Is this happening truly rare?

Before I answer your e-mail let me explain the life cycle of fireflies. Fireflies are also called lightning bugs. These insects however 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 joy of summer, delightful to look at, and fun to catch. Fireflies are about half an inch long and very soft bodied. 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 other fireflies that danger is in the area. The light produced by fireflies is a unique light because nearly 100% of the energy given off by the chemical reaction that produces the light is released as light with very little heat produced due to the process.

Now (finally) to your question. To most homeowners, the flashes appear to occur randomly across the landscape. Fireflies have specific patterns to their light production and there is a call-and-reply interaction occurring between opposite sexes. However it is not uncommon to see many fireflies flash in a synchronous fashion from a particular location due to the shockwave of a clap of thunder or the explosion of a firework. It could be the latter that occurred due to some one still shooting off firecrackers on July 5th.

Firefly Imposters

There are insects out and about that many homeowners believe are fireflies that have 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 that very much look like fireflies but produce no light. They are very beneficial, capturing small insects that visit your plants. They do not damage any plants in the process. So what you saw is not rare, but lot’s of fun.