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A lot going on out there

July 3, 2016
Kevin Williams - Grundy County Conservation Director , Reinbeck Courier

The past few summer evenings might have been a little uncomfortable to sit out enjoy the show but the lightning bugs have been out in great force.

Lightning bugs are not true bugs but instead are beetles. Another common name for the same critter is firefly. But that name is not correct either because they are not flies. I can understand how "lightning fly" might not catch on and the name firefly was perhaps more appealing to folks. I don't understand how lightning bug would stick for a name rather than lightning beetle though. They sound about the same to me.

What did you grow up calling them? Bert Vaux, a linguistics professor at the University of Cambridge, asked 10,000 Americans around the country that question and others relating to regional dialects. If you use "firefly" and "lightning bug" interchangeably, you're in good company. Across the United States, 39.8 percent of respondents report using both terms. But 30.4 percent say "firefly" exclusively and 29.1 percent say "lightning bug." Is lightning bug a mid-western thing? I don't know.

Whatever you call them, they are a specific family called the Lampyridae. There are 124 species of fireflies in the United States and Canada, mostly in the East and South. Like all beetles, the fireflies have a complete life cycle consisting of four stages: egg, larva, pupa and adult.

The adults we see now live for one to two weeks. They may feed on nectar and pollen or other insects, but most of the time is spent in the process of reproduction. The flashing lights are an integral part of the process. The lights help the males and females of the different species find and recognize each other.

After mating, the adult females lay their eggs in moist places such as in tall grass and under mulch and leaf litter. The eggs hatch yet this summer and the larvae live until next summer when they complete the transformation to the adult stage.

Lightning bug larvae are found in moist areas such as under the loose bark of dead trees, under mulch and debris and within moist, loose soil. The elongate, wormlike larvae have six legs and are usually brown. The full-grown length is about 3/4 inch. The larvae are predacious and feed on small insects, worms, snails and slugs.

Lightning bug larvae and adults produce light by an interesting reaction of chemicals and enzymes. The light produced is a "cold" light. That is, the chemical reaction produces nearly all light and very little heat. In contrast, the incandescent light bulb produces only 10% light and the remaining 90% of the energy goes to heat.

The females locate a site near the ground on some sort of vegetation and let the males come to them. The light flashing is regulated according to a genetically fixed pattern and is used by the adults for courtship. Each species has a distinctive pattern of flashes, varying in flash number, duration, interval between flashes, motion accomplished during the flash, height of the flash above ground and so forth. The males and females recognize their own species' flash and get together as a result of the illumination.

So the next time you stop to observe a bean field alive with the flashing of hundreds of thousands little lights, remember, there's a lot of communication happening out there. Males sorting out females and species sorting out species.



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