228 LEAF-MINING INSECTS 



The outstanding difference between this miner and Fenu- 

 sid miners is in the character of the anal segment. The 

 chitinous arcs almost surrounding the base of the anal pro- 

 legs allow the use of this area as a sucker in progression and 

 in getting a purchase for mining operations. Holding with 

 this it is also able to bend the forepart of the body from side 

 to side more easily, a process which is aided and abetted by 

 a greater use of the thoracic legs than Fenusid miners seem 

 to exercise. When the cuticle above the larva is lightly 

 touched with a needle it may be seen to take firm hold with 

 the anal sucker and shake the body up and down vigorously 

 ■ — possibly a defensive action against parasites. If probed 

 a second time it may shake itself again or may twist and 

 turn itself away to another part of the mine. 



In the sixth instar the larvae leave the mine by cutting 

 through the upper cuticle. They enter the ground and 

 there spin a thin cocoon of silk. The half -finished cocoon 

 of a larvae sifted from the earth in a breeding box was found 

 to be pale brown, composed of silken stuff spun into a parch- 

 ment-like sheet, with a somewhat rough outside and a very 

 smooth inside surface. 



The miner are of the blotch type with the pellets of 

 excrement more or less grouped and localized in the mines. 

 The completed mines are about 30 mm. long by 10 mm. wide, 

 or of similar area in different proportions of length and 

 breadth. The position of the mines seems to be somewhat 

 influenced by the size and position of the main veins. 



SCHIZOCERINAE 1 



Our knowledge of the habits of the subfamily is still quite 

 incomplete. The genus Schizocerus contains both leaf- 

 mining and free-feeding forms. Yuasa (1922) speaks as 

 though all of the species of Schizocerus may be leaf-miners 



1 Modified from Frost, 1925. 



