28 



PARASITES OF THE DOMESTIC ANIMALS 



m-aculatus (Fig. 13) and A. punctipennis have been most often observed 

 in the United States. While elaborate keys and tables are necessary even 

 to the entomologist for more exact differentiation, it is not a difficult 

 matter to decide whether a mosquito is or is not a transmitter of malaria, 



Fig. 13. — Anopheles quadrimaculatus: Adult: male at left, fe- 

 male at right — enlarged (after Howard, Bui. No. 25, Bureau of 

 Entomology, Dept. of Agr.). 



the two genera Ciilex and Anopheles being readily distinguished by the 

 following more prominent characteristics : 



The adult Culex, when at rest upon a wall, usually holds the body 



Fig. 14. — Anopheles at left, Culex at right — enlarged (after Howard, Bui. No. 25, 

 Bureau of Entomology, Dept. of Agr.). 



parallel with the wall, or with the abdomen slightly inclined toward it, 

 the angle formed by the abdomen with the head and thorax giving a 



