9 6 



ANIMAL BIOLOGY 



each; No. 25, Notes on Mosquitoes of the U. S., 10c. ; No. 42 

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



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

 Cotton Bolhvorm, 25c. ; No. 51, 



The Mexican Boll Weevil, »>5c. 

 Bureau of Plant Industry — 

 Bulletin No. 88, Weevil-resisting 

 Adaptations of the Cotton Plant, 

 ioc. This gives an instructive 



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



enemy. 



FIG. 186. — Gall fly (enlarged) and oak 

 gall with larva, and one from which 

 a developed insect has escaped. 



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, holding jaws; ul, under lip; kt, jaw fingers; It, lip fingers 



y 





vm. M-. 



