106 



FIRST BOOK OF ZOOLOGY. 



Some of the nuts will be empty, because the gall-insects 

 have already escaped. 



Galls are also produced by other kinds of insects. The 

 following figure, which represents a gall common on the 

 golden-rod, is produced by a two-winged fly. The figure 

 represents the stem or stalk unnaturally swollen, the swollen 

 portion being the gall, within which the larva, pupa, or per- 

 fect insect, may be found if the creature has not already 

 escaped. 



FIG. 103. GALL ON GOLDEN-KOD STALK.-^P, Pupa removed from the Gall. 



Let the pupils arrange in their collecting-box a leaf with 

 the nut attached, a nut cut open showing the pupa-case, and 

 the insect pinned. 



97. Only a few brief lessons have been given represent- 

 ing the life-history of a butterfly, mud-wasp, mosquito, spit- 



