198 



LEAF-MINING INSECTS 



has ten series of punctures and three of the interstices form 

 elevated ridges. These beetles are to be seen apparently 

 motionless upon the leaves; but if they be closely examined 

 they will be found feeding. While the leaves are young 

 they eat out small oblong holes but later in the season they 

 eat only part way through the parenchyma. The beetles 

 are usually rather inactive and walk but slowly. If dis- 

 turbed, however, they take flight and go for a long distance 

 before settling again. 



The eggs are laid on the underside of locust leaves in 

 small masses of three to five, glued together, and partially 



Fig. 62. The leaf -mining locust beetle Chalepus dorsalis. a, adult; 6, 

 larva; c, pupa. (From Chittenden.) 



covered with excrement. The first egg of the mass is laid 

 flat on its side and the others partly overlap the first one 

 and, therefore, stand obliquely, with one end of each egg 

 touching the leaf surface. A brown spot soon appears on 

 the upper leaf surface, marking the location of the egg mass 

 beneath. 



The larvae on hatching enter the leaf under the protection 

 of the egg mass, all through a single hole that is made by 

 the larva that hatches first, and all of them occupy one 

 common mine. They consume all the mesophyl within 



