The Lampyridae are a family of insects in the beetle order Coleoptera with more than 2,000 described species. They are soft-bodied beetles that are commonly called fireflies, glowworms, or lightning bugs for their conspicuous use of bioluminescence during twilight to attract mates or prey. Fireflies produce a "cold light", with no infrared or ultraviolet frequencies. This chemically produced light from the lower abdomen may be yellow, green, or pale red, with wavelengths from 510 to 670 nanometers. Some species such as the dimly glowing "blue ghost" of the Eastern U.S. are commonly thought to emit blue light, although this is a false perception of their truly green emission light, due to the Purkinje effect.