SB 

 818 

 C578 

 ENT 



Circular No. 40, Second Series. 



United States Department of Agriculture; 



DIVISION OF ENTOMOLOGY. 



HOW TO DISTINGUISH THE DIFFERENT MOSaUITOES OF NORTH 



AMERICA. 



In Circular No. 13, of thi.s .series, the writer di.scii.s.sed briefly the 

 habits of one of our commonest mosquitoes {Culex pungent) and some 

 what at length the remedies to be used against all mosquitoes. This 

 account was abbreviated from the more detailed treatment of the sub- 

 ject in Bulletin No. 4, new series, of this Division. 



Since the publication of this circular and of this bulletin wide- 

 spread interest has been attracted to the subject of mosquitoes and 

 their habits and also to the specific and generic distinctions Avhich 

 exist between dilierent forms. This interest has arisen from the dis- 

 covery that certain mosquitoes are intermediary hosts in the develop- 

 ment of the micro-organisms of malaria. The connection between 

 mosquitoes and malaria, although originally suggested in recent timeB 

 by an American physician, A. F. A. King, was first demonstrated by 

 experimental work carried on ])y the English surgeon, Ross, the Ital- 

 ians, Bignami, Grassi, and Bastianelli, and the German. Koch, while 

 the American, McCallum, has followed out the life history of a mala- 

 rial parasite of the common crow. 



The latest work of the foreign investigators shows that not only in 

 South Europe but also in India and in West Africa only mosquitoes 

 of the genus Anopheles are concerned in the transmission of the 

 human malarial parasite, although mosquitoes of the genus Gulex are 

 connected with the transmission of the malarial diseases of birds and 

 possibly of other animals. These conclusions have been confirmed by 

 the Americans, W. S. Thayer, F. N. Berkeley, and All)ert Woldcrt, 

 for America, so far as their work has gone. The latest announced 

 results of the most adxanced investigators seem to show that mosciui- 

 toes form the })rincij)al if not the sole nutans of transmission of mala- 

 ria, and workers in all parts of the world, including many i)arts of the 

 United States, are investigating the subject, more espm-ially in rela- 

 tion to local conditions. 



In the course of this work tnere has arisen considerable difficulty in 

 the identification of local species of mosquitoes. The literature of 

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