78 LEAF-MINING INSECTS 



inal head. The pupal skin now slits open on the median 

 line of the first and second thoracic segments and part of 

 the head. After the usual wriggling movements the adult 

 frees itself from the pupal skin. It expands its wings at 

 once but crawls up hanging them backwards, and very 

 quickly it is in condition for flight. 



The flight is described as weak and somewhat irregular. 

 The adults may be taken in the early spring about their host 

 trees. Williams (1908) found a California species (E. 

 cyanospor sella) among oak trees at the base of Mt. Tamal- 

 pais, by disturbing them from the trunks of the trees early 

 in the morning. "Their flight is rather weak, but hard to 

 follow on account of the small size of the insect. They 

 sometimes feign death, folding their wings like a caddis 

 fly/' 



At least in the birch forests of Norway, members of this 

 genus have become a considerable pest, though, to be sure, 

 their attack is short-lived. 



