TORTRICOIDEA, PYRALIDOIDEA AND NOCTUOIDEA 177 



their work as leaf-miners. They begin to mine, mostly downward, 

 scraping off the chlorophyll from the upper and lower epidermis 

 of the leaf. They eat out the transverse partitions, leaving the 

 longitudinal partitions and the fibro-vascular bundles undisturbed 

 except when occasional larvae cut through to get in other channels. 



Fig. 53. The life history and work of Arzama obliqua. (After Claassen.) 

 A, larva; B, egg removed from cluster and highly magnified; C, pupa; D, 

 egg cluster; E, a leaf of cattail showing at the left the egg cluster where the 

 miners enter, and at the right their exit holes; F, adult moth; G, young 

 larva; H, last larval segments from above; / and J, older larvae as stem 

 borers; K, the mining operations of another Noctuid larva, Nonagria 

 oblonga. 



A few of the larvae may first mine upward toward the tip of the 

 leaf, but soon they all proceed downward, moving abreast along 

 the channels. After the larvae have mined down for a distance 

 of 20 to 24 inches, they molt in the mines and immediately after- 

 ward leave the mines through a little exit hole which is usually 



