NOTES ON THE BIOLOGY OF SOME COMMON LAMPYRIDÆ

Abstract

1. The fireflies studied are luminous both in the larval and adult states, except Pyropyga fenestralis, which is luminous only during larval life. 2. In the luminous species the light-organ of the male is better developed and more brilliant than that of the female. In Photurus pennsylvanica, however, the light-organ in the female is nearly as large and as brilliant as that of the male, but in the other luminous species the organ of the female is limited to a small area on the sixth abdominal segment and it emits a rather faint light. 3. The light-organs of the adults undoubtedly function chiefly in bringing the sexes together. The nature of the flash differs for each species, so that members of the same species can readily recognize the flash of the opposite sex. The males and females of certain species, at times, respond to the light of a small flashlight, indicating that this is not always true. 4. In all these luminous species, except Photurus pennsylvanica, the female orientates her abdomen so that the light emission is in the direction of the male. 5. In all the species studied the larval light-organ degenerates and, in the luminous species, separate light-organs are developed, which function during adult life. 6. In the case of Photinus consanguineus, synchronous flashing was observed in which a few leaders, by flashing, acted as a stimulus to the discharge of the flashes by the others, thus bringing about the flashing in unison of the whole group. 7. The adult fireflies were not observed feeding, except the female of Photurus pennsylvanica. She was found to be very voracious, feeding chiefly on the adults of smaller fireflies, but at times she was found to be cannibalistic. 8. The larvæ of all species were found to be predaceous, feeding on snails, earthworms and numerous species of insect larvæ, especially cutworms. They are at times quite voracious, and it seems evident that they are of considerable economic importance. 9. By means of their hollow mandibles, the larvæ eject a portion of the mid-intestinal juices into its host, thereby paralyzing it, and later digesting it so that when the food is taken into the body it is in a digested or nearly digested condition. 10. The larval life, at least, in most of our native fireflies, extends over a period of two years, during which time the larvæ live on or near the surface of the ground. 11. All species that were studied hibernate as larvæ underneath stones, a short distance under the ground or near the surface, often in specially constructed chambers. 12. Pupation takes place in moist earth under stones, or in specially constructed pupal-cells at the surface of the ground. The pupal cell of Photurus pennsylvanica is made of short, ribbon-like pieces of earth, which the larva masticates and constructs into a lattice-like dome. 13. The pupæ retain the larval light-organs which function throughout the pupal period. This period was found to be from seven to eighteen days according to the species. 14. The adults live for a period of two to four weeks, during which time they deposit their eggs on the ground about the roots of grass and moss.