196 LEAF-MINING INSECTS 



cells of a single layer (usually the palisade layer). Full 

 depth mines are, however, the rule in this family, with equal 

 visibility from either side of the leaf, and blotch mines are 

 much commoner than linear ones. 



As in the Lepidoptera, the more specialized show a prefer- 

 ence for the longer enduring leaves of woody plants. The 

 leaf-mining flea-beetles of the genus Phyllotreta feed on 

 cruciferous plants. Those of Hippuriphila feed on docks 

 (Rumex). 



Among the various tribes of this great family only three, 

 have representatives that mine in leaves. Among the flea 

 beetles leaf mining is the exception, but among the "little 

 leaf -bee ties" (so Harris calls them) it is the rule. The larvae 

 of the former are but little specialized for mining, being almost 

 cylindrical and possessing well developed thoracic legs. They 

 are not found in very thin leaves but rather in the thicker 

 more succulent ones, as those of some of the cresses. The 

 larvae of the latter are somewhat depressed. They have 

 short, widely separated thoracic legs. The abdominal seg- 

 ments protrude at the side as somewhat triangular tubercles. 

 The mines which these make are somewhat inflated and 

 bladder-like. 



Hispinae. These little wedge-shaped leaf -beetles are more 

 abundantly represented in the tropics than farther north. 

 The larvae of several species are known to be leaf-miners. 

 The adults have the antennae inserted close together. In 

 most of the species, as the name Hispa suggests, the wing 

 covers and prothorax are roughened by deep pits or are 

 covered with long sharp spines. Many of the beetles are 

 brilliantly colored. 



Hispa 



Of the genus Hispa, from which this tribe takes its name, 

 we have not, so far as known, any North American repre- 



