9 6 



ANIMAL BIOLOGY 



each; No. 25, Notes on Mosquitoes of the U. S., IOG. ; No. 42 

 Some Insects attacking the Stems of Growing Wheat, Rye, Barley, 



and Oats, 5c. ; No. 50, The 

 Cotton Bollworm, 25C.; No. 51, 

 The Mexican Boll Weevil, *2$c. 

 Bureau of Plant Industry 

 FIG. i86.-Gall fly (enlarged) and oak Bulletin No. 88, Weevil-resisting 

 gall with larva, and one from which Adaptations of the Cotton Plant, 

 a developed insect has escaped. JOC> This giveg an i nstruc tive 



account of the struggle of a plant for existence against an insect 

 enemy. 



FIG. 187. PLAN OF MOUTH PARTS OF THE INSECT ORDERS. A, straight 

 wings, nerve wings, false nerve wings ; B, joined wings ; C, scaly wings ; D, half 

 wings ; E, two wings. 



ol, upper lip ; ok, biting jaws ; uk t holding jaws; ///, under lip; kt t jaw fingers; #, lip fingers 



