1919] King: Biology of the Carabid . 385 



the lid of the cell being formed from a thin layer of mud which 

 covers the dorsal portion of these segments. After the deposi- 

 tion of the egg the tip of the abdomen is withdrawn and is again 

 used to bend down the dorsal flap or lid and close the cell, the 

 lid of which is self sealing, because of the soft texture of the mud 

 at the time of construction. Thus the mud cells of Chlaenius 

 may be compared to a pouched envelope in form and mechanism. 

 The folding flap and the sealing of the edge when the soft mud 

 of the flap comes in contact with the opposite lip of the cell 

 is not different in principle from that of a common envelope. 

 The clay cells of Chlaenius tricolor (Plate XXXI, Fig. 3a) show this 

 structure quite distinctly. 



As concerns the number of cells made by an individual 

 beetle, I have noted that C. impiinctifrons may construct seven 

 to twenty cells during one night and eighty-two cells in a 

 season. 



Feeding Habits of the Larv^. 



The cell building habit of these Carabids presents several 

 interesting biological questions. Among these is one relative 

 to the feeding habits of the issuing larvae. As concerns this, 

 there is but a single note by, Claassen, Annals of the Ent. Soc. 

 Amer., XII, 96, 1919. I quote the following: 



"Various kinds of food were offered to the young larva 

 {of Chlaenius impunctifrons) ; larvae and pupae of Lymnaecia 

 phragmitella Stainton, larvae of Nonagria oblonga Grote, Arsi- 

 lonche albovenosa Goeze, and Arzama obliqua Walk. Flies and 

 fresh meat were also offered to the larva. At first the young 

 larva fed somewhat on flies and on larvae and pupae of L. 

 phragmitella, but it showed a decided preference for the little 

 larvae of A . obliqua. 



During the second and third instar all other food was refused 

 except larvae of A. obliqua. 



All the above mentioned Lepidoptera are inhabitants of 

 Typha. A. albovenosa is an incidental surface feeder on the 

 leaves; L. phragmitella lives in the heads of Typha, while A. 

 obliqua and A^. oblonga both begin their larval activities as leaf 

 miners, later becoming solitary stem borers. 



It is possible that the larvae of Chlaenius impunctifrons 

 feed altogether on the larvae of A. obliqua. The former hatch 



