Firefly (Photinus pyralis): Photo by Terry Priest. http://www.frfly.com/tutorial/firefly-photography.htm
Fireflies or lightning bugs are nocturnal, winged beetles that produce a yellow, green, or pale red light from light-emitting organs in their lower abdomen by a process called bioluminescence. Even their larva emit light, hence the name glowworm is occasionally used but should not be confused with another distinct beetle family. Larval bioluminescence is a warning to predators that fireflies are distasteful and may be toxic. In some fireflies, even the eggs are bioluminescent. After mating, a female will lay her eggs on the ground amongst leaf litter, for example, or just barely below the surface of the ground. Three to four weeks later the eggs hatch and the young larvae feed all summer on slugs, snails, worms and other insects. Firefly larvae hibernate during the winter and emerge
in the spring to feed for a few more weeks before pupating into adults that we see during darkness. Firefly populations seem to be declining probably from loss of natural habitats like meadows and woodland edges by homes with landscaped lawns. Pesticide use on lawns and gardens as well as the use of DDT to kill mosquitoes has also had a damaging effect on fireflies.