150 



FOREST ENTOMOLOGY. 



ember and October the gall becomes loosened and falls to the ground, 

 and a few may remain, but only inquilines and parasites are reared 

 from those adherent galls." The flies are said to be difficult to rear 

 from the galls, as after the galls are mature a year and a half passes 

 before the appearance of the flies. 



9a. Andricus curvator (Htg.) 1 



This alternating generation with Aphilofhrix collaris is a very 

 common gall, and may be found about the beginning or middle of 



Fig. 144. G'aftso/ Audi icus 

 curvator. 



Fig. 14o. Injury dour to leading thoot 

 by gall of Andricus curvator. 



June. The galls are formed on the ribs of the leaves. They form 

 irregular thickenings of the leaf-surface, and cause the leaf to twist 

 inwards (fig. 144). Sometimes we find the extreme tip of the twig 

 affected by the gall-formation, and, as a consequence, a swelling 

 takes place where the terminal shoot bends, and grows at right angles 



1 From this point the alternation of generations is not followed. 



