96 LEAF-MINING INSECTS 



The pupa. The pupa is rather variable in size, the average of 

 five being 3.35 mm. by 0.95 mm. The color when first formed is 

 rather uniformly pea green, later becoming much darker, varying 

 with age. The general color of the thoracic region and head is 

 dark brown to blackish. The abdomen is dark green, yellowish 

 caudad; the caudal margin of the rather distinct segments is 

 brown. Leg and wing sheaths free. 



In the vicinity of Washington the mid-summer generation has 

 a life cycle of about 33 days. 



FAMILY LYONETIDAE 



In this family are included a number of minute moths, 

 having many structural characters in common, but having 

 larvae whose form and habits fall into three principal groups, 

 as follows : 



I. The iA/onetia group, whose tissue feeding larvae are 

 miners through life, but pupate outside the mine, generally 

 attached beneath a leaf under more or less protection of 

 spun silk. The mines are first serpentine and then blotched, 

 and are usually filled with scattered blackish frass. 



II. The Phyllocnistis group, whose legless, sap-feeding 

 larvae shear through the palisade cells of the leaf during 

 four feeding stages; then, becoming more cylindrical in 

 form, rest in a chamber formed in the leaf at the end of the 

 mine, during a final larval stage, and then pupate in the 

 same chamber. The mine is narrowly serpentine through- 

 out, and is of the almost invisible "snail trace' ' type, with 

 hardly more than a central tracing of frass. 



III. The Bucculatrix group, whose ordinary tissue-feeding 

 larvae are equipped wdth good thoracic legs, and make small 

 serpentine mines during the first stage only, feeding there- 

 after openly from the surface of the leaf. 



Group I 



Of the first group of the Lyonetidae we have in North 

 America representatives of four well-know T n genera, Lyon- 



