NOTES ON THE BIOLOGY OF THE FIREFLIES. 
WALTER N. HESS. 
(DePauw University.) 
During the past year I became interested in studying the biology of the 
fireflies, and after looking up the literature on the group I concluded that 
little was known regarding them except what had been learned from a study 
of the adults. 
The following species were studied: Photinus consanguineus Lee., Pho- 
tinus scintillans Say, Photurus pennsylvanicus DeGeer, and Pyropyga fene- 
stralis Mels. Most attention, however, was given to Photurus pennsyl- 
vanica, and this paper will be limited to a discussion of that species. 
This firefly, Photurus pennsylvanica, is one of the largest and most 
common of our native species. As is common of our luminous fireflies, 
the adults are usually found only at night since they spend the day con- 
cealed underneath moss or grass, although occasionally specimens were 
found clinging to the underside of leaves of low vegetation. Like many 
other insects, this species has well defined centers of distribution, it being 
rarely found except along marshy or moist localities. Some of the smaller 
species of fireflies, however, seem to prefer the drier regions. 
Many insects during their adult life eat little or no food, but the adults 
of this species, especially the females, are yery voracious in their feeding 
habits. These females were commonly observed devouring other species of 
fireflies, and not infrequently the males of their own species. 
In the case of nearly all our luminous fireflies the female never flies, but 
remains on or near the ground and there awaits her mate. In this species, 
however, the female is also an active flier. 
It is agreed by most students of fireflies that the light-emissions serve 
to bring the two sexes together. In our smaller native species there is 
a definite interchange of flashes, by which the male is able to find the 
female. In this species both sexes are active fliers and they flash frequently 
whether in the presence of each other or not. In no case was there observed 
a definite exchange of flashes between the sexes of this species. Yet, on 
several occasions. while holding females in my hand, males flew to them, 
and on two occasions while holding males, females flew and alighted be- 
side the captured males. This would lead one to believe that there is a 
definite sexual attraction between the sexes of this species, and that the 
females having become active fliers, are also attracted to the males. 
The characteristic place for the oviposition, by the females, is at the base 
of grass or moss in damp loamy soil. The eggs which are deposited about 
the first of June are usually placed in little cracks or depressions in the 
earth, and there they remain for a period of approximately 26 days, when 
they hatch into little larvae. These little larvae, which hatch about July 
first, require nearly two years to complete their growth before they trans- 
form into adults. 
The larvae resemble to a considerable extent the habits of the adults as 
they are active only at night. This makes it rather difficult to study their 
