BIOLOGY OF SOME COMMON LAMPYRID^. 63 



the glow becomes very faint and it frequently is not perceptible 

 even while holding the larvse ventral side up in a dark room. 

 By moving the insects about so as to agitate them the lights 

 usually become visible. It seems probable that the brilliancy 

 of the glow is in direct proportion to the activity of the larvse. 



The larvae which were kept in confinement at the insectary 

 were found to go underneath stones, or enter cracks in the soil, 

 late in October, in preparation for hibernation. Some constructed 

 about themselves earthen chambers, while others occupied natural 

 depressions in these protected places. In no instance were they 

 found lying on their dorsal side, such as is characteristic of the 

 pupae. 



During the warm nights of April the larvae leave their winter 

 quarters and go about in search of food. At this season their 

 little lights can again be seen as they wander about in their 

 natural habitats at night. 



Since this species of insect lives as a larva at the base of grass 

 in moist loamy soil, and since it does not enter the ground, or 

 seek other natural means of concealment in which to pass the 



l-v... 



FIG. 13. Photuriis pennsylvanica partially constructed pupal chamber. 



pupal period, as many members of the Coleoptera, as well as 

 some Lampyrids do, it constructs a small earthen chamber in 

 which to pass this period of transformation. 



A suitable spot on the surface of the ground, usually at the 

 base of moss or grass is chosen, and at once the larva begins 

 building a lattice work of soft earth over itself, in the shape of a 

 small dome (Fig. 13), by which means it conceals itself , in about a 

 day. In the construction of this cell the larva removes earth 

 from underneath itself by means of its mandibles. This it 

 masticates and mixes in its mouth for a period of about half a 

 minute. It then extends its head to the lattice work of the 



