MOUNTAIN TREES 



gall begins to grow, and never ceases its 

 abnormal development until the larvae 

 reach their full growth. Upon maturing 

 of the larvae, the gall begins to dry up 

 and harden, thus forming a snug 

 house for the insects during their period 

 of pupation. Later upon development 

 into full grown flies, the tiny insects 

 gnaw their way out of the dead galls to 

 prick in new leaves and lay eggs for an- 

 other life cycle. 



These gall flies are tiny two-winged 

 insects, the largest being not more than 

 one-third of an inch long. Curiously, 

 the individuals of some species are all 

 females. An additional interesting fea- 

 ture is the fact that often in the same 

 gall with the gall makers are other in- 

 sect guests or parasites. These "degen- 

 erate loafers," are often present in 

 amazing numbers and though they have 

 done nothing in the making of the gall- 

 house, feed upon the sap and enjoy all 

 the securities of the home of the host. 



