74 WALTER N. HESS. 



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 flash- 

 light, indicating that this is not always true. 



4. In all these luminous species, except Photurus pennsyl- 

 vanica, 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 bring- 

 ing 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 larvae of all species were found to be predaceous, 

 feeding on snails, earthworms and numerous species of insect 

 larvae, 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 larvae eject a 

 portion of the mid-intestinal juices into its host, thereby paralyz- 

 ing 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 larvae 

 live on or near the surface of the ground. 



