254 



LEAF-MINING INSECTS 



occurs early in the season. By the middle of May the 

 mines become very noticeable upon the lower leaves of the 

 elms. In the course of a couple of weeks it is almost im- 

 possible to find a larva as all have transformed. Some 

 difficulty has been experienced in rearing this species and this 

 is probably due to the fact that the majority of the puparia 

 remain dormant during the summer and adults do not emerge 



Fig. 79. The corn blotch leaf -miner Agromyza parvicornis. A, dorsal 

 view of adult; B, antenna 9 ; C, head of d" ; D, hypopygium of c? ; E, Oviposi- 

 tor, a, egg; b, newly hatched larva in mine; c, feeding punctures of adults. 

 (From Phillips.) 



until the following spring. A few flies have been secured 

 from puparia which transformed in the early spring. 



The corn-blotch leaf -miner (Agromyza parvicornis) mines 

 several species of grasses of which wheat and corn are the 

 most important. It is apparently indigenous to North 

 America, now having a wide distribution over the United 

 States. It can safely be called a common species. 



Phillips (1914) has studied the life history of this leaf- 

 miner and we take our account from his investigations. 



