"With few exceptions, luminous insects throughout the world belong, broadly speaking, to one family of Beetles, the , or to give them their popular name, the Fireflies and Glow-worms. The most important exception to this statement is afforded by the Fireflies of the West Indies and Central America, locally known as " Cucujos," which, though still Beetles, belong to quite a different family, the or Skipjacks. ... Though usually present to a greater or lesser degree in both sexes, the luminous property is generally developed much more highly in one sex than in the other. When it is the male beetle that possesses it in the greater degree, the light is shown when the insect is on the wing, and is generally of an intermittent or flashing character, and gives to the insects their popular name of Fireflies. On the other hand, when the power of luminosity is the more highly developed in the female beetle, the character is usually associated with a more or less complete absence of wings, and the insect becomes merely a crawling, unpleasant-looking, worm-like creature, generally known in fact as a Glow-worm, which nobody who is not an entomologist would ever dream of calling a Beetle. The males of these insects are winged, in form closely resembling the Fireflies, and are totally unlike their spouses. The consequence of this utter dissimilarity between the two sexes of one species is, that it is not easy to co-relate them properly in our collections."