PlIYL UM AR THRO POD A 



279 



any rate with few joints, usually three. At the end of the 

 series we place such forms as the house fly and tsetse 



fly, in which the pupa 

 is entirely inactive. The Chaetotaxy, 



iii i i or the study 



more highly specialized ofbris ties 

 flies are remarkable for 

 the arrangement of the 

 bristles on the thorax. 

 In addition to the gen- 

 eral covering of fine hair 

 (pubescence), there is a 

 series of regularly placed 

 bristles, the position and 

 number of which char- 

 acterize different genera 

 and species. The bris- 

 tles on the head also are 

 very important. Va- 

 rious Diptera are connected with the propagation of 

 the germs of disease, as we have seen in Chapter 26. 



References 



SHARP, D. "Insects." Cambridge Natural History, Vols. V, VI. This is 



the best general treatise on insects. 

 COMSTOCK, J. H. and A. B. Manual for the Study of Insects. Especially 



useful for the figures of wing venation. 

 KELLOGG, V. L. American Insects. Holt & Co. 

 HOWARD, L. O. The Insect Book. Doubleday, Page & Co. The numerous 



plates are particularly useful, but there is no direct connection between 



the plates and the text. There is a good bibliography. 

 RILEY, W. A., and JOHANNSEN, O. A. Handbook of Medical Entomology. 



Comstock Publishing Company. 

 BRUES, C. T., and MELANDER, A. L. Key to the Families of North American 



Insects. 



SMITH, J. B. Explanation of Terms Used in Entomology. Brooklyn Ento- 

 mological Society. 

 LUTZ, F. E. Field Book of Insects. Putnam's Sons. A convenient and 



useful semipopular handbook. 



From Bulletin 67, U. S. National Museum 

 FIG. 100. A crane fly (Tipula). 



