212 



INSECT LIFE. 



a compound gall containing many cells, in each of 

 which a larva gets its growth. The mossy-rose-gall, 

 which occurs on the stem of the sweetbrier (Fig. 

 179), is a familiar example of a many-celled gall. 



Fig. 179. — The mossy-rose-gall. 



In the two kinds of galls figured here the larva 

 lives in a closed cell which has no opening until one 

 is made by the full-grown larva for his escape. Most 

 galls of this kind are made by insects of the family 

 Cynipid^ (Cy-nip'i-dae) of the order Hymenoptera. 

 To this family the name gall-flies is restricted, al- 

 though many other insects produce galls. Fig. 180 

 represents an adult gall-fly greatly enlarged. 



The largest galls that occur on forest trees are 

 produced by gall-flies, but there are other kinds of 



