National Geographic : 1970 Jul
student who joined us when his classes let out, seemed to appreciate success in the hunt even more than the modest wage I paid. Isaac whistled constantly as we searched. From a distance I could judge his luck by his tune; the better the hunting, the livelier his whistle. Phrixothrix means "with bristling hair," referring to the tiny hairs on the beetle's body. I was delighted to learn recently that the species, a new one to the scientific world, is being named in my honor. The insects hatch from eggs laid underground and pass by far the greater part of their lives perhaps a year or longer-as larvae. Many of my specimens transformed into pupae in captivity. Males remained in the pupal stage for 25 days, and females nine to ten days, before becoming adults. In all three stages they had the ability to luminesce. Monogamous Males Take Fickle Mates The male metamorphoses into a small winged beetle (page 65). Attracted to light, it is relatively easy to collect; specimens have been captured from Argentina to as far north as Costa Rica. Of course females occur in the same range, but rarely have naturalists found them. The female spends most of her brief adulthood in an underground cell, perhaps going to the surface once to announce her readiness to mate. Never acquiring wings, the female outwardly resem bles a larva as she emerges from the pupal stage -a characteristic of all known species in the Phengodidae family of beetles. Males seem attracted to females not by lumi nous signals, as with fireflies, but by a faint scent. Males mate once; a female may mate with sev eral males. But she will lay eggs only once about three dozen pearly-white spheres, which soon turn reddish-brown (page 65). Adult male beetles emitted greenish-yellow light from the abdomen, but I could not detect the bright red of the head lamp. Mature females gave off both colors. Bioluminescence in insects, fish, and other organisms has been studied by scientists for many years.* They believe that railroad worms produce light as fireflies do, by oxidizing a chem ical called "luciferin." An enzyme, luciferase, must be present for the chemical reaction to yield a glow, just as enzymes serve as catalysts in the human body. *For an explanation of firefly luminescence, see "Torch bearers of the Twilight," by Frederick G. Vosburgh, NA TIONAL GEOGRAPHIC, May 1951. Dr. Paul A. Zahl described luminous marine organisms in "Sailing a Sea of Fire," July 1960, and light-emitting fish in "Fishing in the Whirlpool of Charybdis," November 1953. 60 Diner merges with dinner as a railroad worm (above) eats its way through a mil lipede twice its size. When confined to gether, the larvae sometimes eat each other.