io6 



NORTH AMERICAN DIPTRRA. 



Head well formed, enclosed in a chitinous covering; 

 with compound eyes, single-jointed antennae, a group of 

 hairs before the oral orifice, toothed mandibles, maxillae, 

 and single-jointed palpi. Thoracic segments consolida- 

 ted into a transversely elliptical flattened mass ; abdomen 

 with nine slender and moniliform segments, the eighth 

 with a dorsal, respiratory opening, often prolonged into 

 a chitinous tube ; last segment furnished with a chitin- 

 ous plate, and usually with four delicate anal append- 

 ages. The body has setae in tufts or singly, usually 

 more or less conspicuously feathered. From other aquatic 

 nematocerous larvae, the mosquitoes are distinguished 

 by the presence of the mouth-brush, the shape of the 

 anal segment and the absence of abdominal feet. The 

 larvae of Dixa and the Corethrinae are practicably indis- 

 tinguishable from those of the Culicinae, save by minor 

 characters.* 



35- Culicidse. i, Megarhinus, wing; 2, Megarhinus^ head, 

 male; 3, Aedes, wing; 4, Hcemagogus, bead, female; 5, front claws 

 of Hcemagogus, male; 6, Wyeomyia, head of female; 7, Corethra, hind 

 tarsus. 



TABLE OF GENERA. 



Proboscis short, not adapted for piercing. . . Corethrinse. 

 Proboscis much longer than the head, firm, adapted for piercing. 



Mosquitoes. ........ Culicinae. 



*I especially commend to the student interested in this family of flies 

 the comprehensive and richly illustrated Report upon the Mosquitoes 

 of New Jersey (1904), by Prof. J. \\, Smith. 



