National Geographic : 1962 Jul
Wing-borne Lamps of the Summer Night The firefly species most prevalent in these jungle-girt mountains this time of year is Photinis pallens (pale shining light). Similar species of Photinus are seen on summer nights in the eastern United States. Scientists have given us the answers to many questions about Jamaican firetlies their classification, anatomy, flash patterns. But as to details of their life cycle, the record is nearly blank. Based on what we know about related fire flies of the northern Temperate Zone, how ever, we can make some good guesses. It is likely that eggs of the tropical species are laid in moist humus and hatch in about three weeks. The larvae remain in the forest duff for up to two years, it is believed, feeding on slugs that are larger than themselves, on snails, and on the larvae of other insects, before they pupate and emerge as adults. The male Plhotinus pallens exhibits two types of light: a bright though not intense flash usually produced when the insect is stationary and repeated at quarter- to half second intervals, and a brilliant one produced at irregular intervals in flight. So intense is the latter flash that if one's eves are near, the effect may be momentarily blinding, as if a miniature flashbulb had gone off. Female Responds to Male's Signal The female does little flying; in some spe cies, none at all. She selects a prominent position on a blade of grass or twig, then merely sits and waits. If a flying male flashes nearby, she responds with her own light. The Fireflies in a Box Provide All the Light Needed to Take Their Picture First, author Zahl made a flash photograph (left) of about 100 Jamaican fireflies in a plastic box with transparent lid, surrounded by hydrangeas, marigolds, and nasturtiums. Then, in total darkness, he made a 20-second time exposure with the striking result at right. Though fireflies provide the only light, the flowers still show clearly.