ORDER COLEOPTERA 195 



other, rarely crossing the midrib of the leaf, making a 

 blotch of very variable form, devouring all the tissue be- 

 tween the two layers of epidermis. It lives solitary, except 

 that confluence of adjacent mines may sometimes occur. 

 The cast skins left at the center of the mine among the 

 dried frass indicate that the larva returns here to moult. 

 Here also in this most spacious portion of the mine it trans- 

 forms. The naked pupa, at first soft and white, soon be- 

 comes hard and brown. 



The egg stage lasts about ten days, the larval stage three 

 to four or more weeks; the pupal stage about ten days. The 

 adult lives ten months or more, emerging in August, feed- 

 ing on the uninjured portion of the bulrush leaves, already 

 blotched with mines, until their margins are notched and 

 jagged; and the females, at least, feed again in the late 

 spring when new leaves are available. At Ithaca, New York, 

 they deposit most of their eggs in June. The beetle is 

 about a sixth of an inch long, black, shiny, given to death 

 feigning when disturbed, with short legs and antennae that 

 fold compactly into grooves, making the ventral surface 

 almost as smooth as the back. This bulrush grows on low 

 ground that is often inundated in winter. Where the adult 

 beetles hibernate is still unknown. 



FAMILY CHRYSOMELIDAE 



Leaf beetles 



Among the sixteen genera of this great family that are 

 now known to contain leaf-mining species, there is consid- 

 erable diversity of form and habit. The larvae of all are 

 depressed but some are otherwise little modified in adapta- 

 tion to mining. They have well developed legs and rather 

 ordinary head capsule, but the larvae of Octotoma are leg- 

 less, and strongly wedge-shaped at the front; and they have 

 thin flat mouthparts that are capable of feeding upon the 



