Things that glow in the dark

Lightningbugs or fireflies have a magical effect on kids. Jaded adults outgrow this feeling although occasionally it returns if you happen to see a large population. The magic comes from biological light production, called bioluminescence for short. Lightningbugs is written as one word because the insects are beetles and not true bugs. These beetles provide the best known local source of bioluminescence. As most people know, the taillight mainly gets the two sexes together although a few species seem to also use them for landing lights. There are 125 different species of Lightningbugs in the US and Canada. With a few exceptions all the species have a distinctive rhythm. The exceptions are some predatory beetles that imitate the flashing of certain beetles so they can lure them to their death.

The light comes from a chemical called luciferin being oxidized. The insects control the light by controlling the air supply. As soon as they let the air in, the chemical flashes.

Lightningbugs aren't the only local source of bioluminescence. A lot of people know about foxfire, another natural glow in the dark phenomena. This fungus grows on dead wood. It prefers oak but I once saw it on dogwood. It gets on several other hardwoods but the most likely place to find it is in a mature oak forest. I kthe most likely place to find it is in a mature oak forest. I know sites to find foxfire in Stanley and Montgomery County but haven't seen it in Cabarrus County. Foxfire may be scarcer here but it's more likely I haven't looked in the right places.

Foxfire isn't harmful to living trees. If you notice it, no control is necessary. It does indicate dead wood. So if itís on the root system of a tree that is still partly alive, you need to get the tree checked by an arborist to determine if it is hazardous.

Like the lightning bugs, the foxfire fungus manages to give almost 100% of its energy off as light. In comparison, a regular light bulb only gives off 10% as light.

I have seen glowing fungi on dead maple leaves but don't know if it was the same species as the foxfire I find on oaks.

The larva stage of lightning bugs glows, so they are called glow worms. In addition, the adult females of some lightningbug species don't have wings and looks a lot like the larvae. They are also called glowworms. You can see this type of glow worm in the spring right before you see lightning bugs flying. The larva stage preys on smaller insects and slugs. Lightning bugs are considered beneficial insects since they are harmless and eat other insects.

Another glow worm shows up in the fall of the year. That one is from a different family than regular lightning bugs.

Although I knew about foxfire, lightningbugs and glow worms, an insect I found recently came as a complete surprise. My father had never seen one either, despite over 65 years of wandering the eastern woodlands.

This insect was a cream colored grub almost two inches long, and had several glowing green rings around its body. The intensity amazed me. I readily noticed the glow from 30 feet away. I think four or five would have been as bright as the green chemlights we used in the military and about the same color.

With a little study I learned this is the larvae stage of a beetle in the Phenogodidae family. The adult females look almost identical in size and shape but are a darker color. Adult males don't glow although they do have some amazing antennae. The reference books list 25 North American species in this family but only two are common to this area. Both are in the Phenogodes genus. The book also lists 30 mm as the maximum size. Since this one was close to 50 mm, it definitely was on the large size. The larva stage eats millipedes, so perhaps it had some easy hunting with all the millipedes this year.

Are there any more glow in the dark surprises? I can't be sure. You don't know what you don't know. The only other beetles with glow in the dark capability are a few in the Electridae family. These shine brighter than the lightningbugs we have around here. They live in tropical areas and as far north as Florida and Texas, so I don't expect to see them around here. I found a reference to a glow in the dark fungus gnat that lives in New Zealand caves. I have also heard of microscopic sea life in certain tropical areas that gives off light. So who knows what you might see. Just keep your eyes open the next time you are wandering around in the dark.

Article was written by David Goforth Agriculture Extension agent North Carolina Cooperative Extension Cabarrus County Center.† Visit my homepage http://cabarrus.ces.ncsu.edu/ or http://cabarrus.ces.ncsu.edu/index.php?page=lawngarden or my blog http://gardeninggurugoforth.blogspot.com/

Contact me at David_Goforth@ncsu.edu.† Reviewed 2007.†