The most brilliant fireflies are a species most at home in tropical America. One form—Pyrophorus noctilucus—common in the West Indies and Brazil, attains a length of about one and one-half inches, and has a dark, rusty-brown color. On the upper surface of the first rings of the thorax are two yellowish oval spots, which are brilliantly luminous during the nocturnal activity of the beetle, while on the first ring of the abdomen a still brighter organ is situated. Even the eggs are luminous, and excised portions placed in a damp chamber remain functional for two or three days. The pounded debris of the insect is also luminous. The luminous organs are special modifications of the epidermic cells, which are disposed in two layers, of which the outer alone is luminous, while the inner contains masses of waste products, and is riddled by air tubes. The luminosity depends on a process of oxidation; the oxygen is supplied by the tracheæ, and the brilliancy varies with the breathing process of the insect. On the sleeping or entirely passive insect a soft light may be observed; the real light is only exhibited during active respiration, and may be exaggerated experimentally by blowing in an extra supply of oxygen. Experiments seem to show that the fireflies utilize their phosphorescence to guide their steps.
SOME PICTURED MARVELS OF INSECT LIFE
A MOTHER EARWIG PROTECTING HER FAMILY (See [page 237])
CONTEST BETWEEN TWO MALE STAG-BEETLES FOR A MATE (See [Page 234])
THE SEVEN SPOTTED
LADY-BUG
(See [Page 234])
