76 Zoologica: N. Y. Zoological Society [HI; 3 



19-21. Owing to the minuteness of the particles used in building 

 the cocoon, the care with which they are chosen and the many 

 trips necessary to secure them, the time consumed in completing 

 the structure is considerable. The earliest stage figured (Fig. 6a) 

 was first seen at 8 P. M., July 25. By 6 A. M. the following 

 morning the cocoon was in the stage shown in b. By 12.30 P. 

 M. the small opening had been closed and the large opening was 

 being contracted (c). At 6:30 P. M. a small opening remained 

 (e), and the cocoon was completed an hour later (/). As the 

 first stage must have been the work of the greater part of a day, 

 the structure was probably begun not later than 7 A. M. on 

 July 25th. At least 36 hours of continuous labor, requiring 

 hundreds of trips back and forth between the cocoon and ex- 

 posed patches of living parenchyma on the petiolar wall, were 

 therefore consumed in completing the cocoon. The second larva 

 observed in the act of building its cocoon was even slower, since 

 the latter was first seen on the evening of July 26 in a stage 

 corresponding to Fig. 6a and was not entirely completed till after 

 10 A. M., July 29th. There was nothing to indicate that the 

 first larva rested during the whole period of cocoon construc- 

 tion. While it was working in the manner described, it was 

 occasionally annoyed by some young or half-grown larva enter- 

 ing the cocoon and using it as a hiding place while its architect 

 was away gathering building materials. It was interesting to 

 see the latter on its return oust the intruder, which scampered 

 away with comical alacrity. When the cocoon is completed it 

 is rather smooth externally but may later become rough through 

 the beetles' plastering their frass over its surface. This cer- 

 tainly strengthens the walls of the structure. 



I endeavored to keep the two pupse enclosed in the cocoons 

 which I had seen built, in order to determine the length of the 

 pupal period, but both died when the petioles dried out. The 

 pupal period as inferred from other cases covers, at least, seven 

 days. The callow emerging beetle under normal conditions 

 gnaws a round or elliptical opening at one end of the cocoon 

 and joins the other members of the colony. At first it is yellow- 

 ish white and etiolated, with the legs, dorsal surface of head 

 and prothorax and a transverse band on each segment of the 

 venter pale red. It runs about very actively, nevertheless, and 



