164 LEAF-MINING INSECTS 



Frequently the leaves are scarred or blotched by numerous mines, 

 and sometimes the whole leaf is mined, but in such cases there are 

 several larvae in a mine. The typical form of the mine seems to 

 begin as a point, from which it passes, gradually widening, first to 

 one side, then to the other, in a series of loops, each extending a 

 little farther than the preceding, like a band gradually widening, 

 wound around a cone. The frass is scattered through the mine. 



Fig. 50. A leaf of lamb's quarters bearing a mine of.Chrysopora. 



Such mines are common at Ithaca, New York, in goose- 

 foot leaves in autumn. The accompanying figure of an 

 unusually extended mine show r s at 1, 2 and 3 successive 

 enlargements following successive moultings of the larva. 



