1914] Williams—Prothetely in the Larva of Photuris pennsylvanica De Geer 127 
In the fall of 1913, the writer collected upwards of one hundred 
larvee of our common large firefly, Photuris pennsylvanica DeG., 
in the Arnold Arboretum, adjoining the grounds of the Bussey 
Institution. These larvee, ranging from about 13 to 18 mm. long, 
were in the second and last year of their growth. Under natural 
conditions they should have pupated in May or June of 1914, 
and produced adults a few days later, but, owing to the fact that 
they were kept under artificial conditions, adults emerged in late 
winter as well as in summer. 
1 
Fig. 1. Prothetelous larva of Photuris pennsyluanica De Geer. 
1, dorsal view; 2, ventral view. 
As secured in the field, these larvee appeared to be_ perfectly 
normal. They were examined from time to time in the laboratory, 
and on May 27, 1914, an individual was found with a pair of well 
developed wing-pads on the meso- and metathorax. Two days 
later another such larva was discovered. Photographs were taken 
showing the dorsal and ventral view of one of these larvee anzsthe- 
tized with chloroform, and are reproduced above. It will be seen 
that the wing-buds are here much smaller than the wing-cases of 
