FAMILY CHIRONOMIDAE 157 



Natural History (Insects, Part II), and for details of the genera Wii- 

 liston's North American Diptera. 



THE NEMATOCERA 

 FAMILY CHIRONOMIDAE 



Small midges from .5 to 14 mm. in length ; proboscis somewhat 

 long ; antennae with four to fifteen segments, pilose in the female and 

 plumose in the male. Eyes kidney -shaped; ocelli absent in all species. 

 Thorax strongly arched, scutellum and metanotum small. Wings as a 

 rule straighter in the male than in the female ; costal vein terminating 

 at the extremity of the third longitudinal vein ; subcostal or auxiliary 

 vein not well defined ; first longitudinal vein distinct and abutting 

 the anterior border of the wing ; second longitudinal vein inconspicuous, 

 and sometimes absent ; third long vein well developed, often arising 

 from the first and ending at the anterior border of the wing, rarely 

 at the point. The fourth vein arises from the base of the wing, 

 and is well developed up to the point at which it is united to the 

 third vein ; it -may be forked. The fifth vein is nearly always 

 forked; the sixth and seventh veins are incomplete or often wanting. 

 The wing is rough or hairy, but never clothed with scales. The 

 halteres are bare. The legs are never elongated, and the tibiae usually 

 terminate in a short spur. The abdomen is long and slender. 



The Chironomidae are common midges, many of which are nocturnal 

 in their habits. During the rainy season in the tropics, they are 

 seen in large numbers round a light, the majority of these prove 

 to be males. Their larvae are the well-known blood-worms found in 

 streams and stagnant pools. Some of them build for themselves 

 characteristic tunnels of mud at the bottom of the pool, while others 

 move about freely in the water or wet soil. A few pass their early 

 stages under the barks of trees. The family is an enormous one, 

 and is widely distributed. Kieffer recognizes five subfamilies, of 

 which only one, the Ceratopogoninae, is known to contain blood- 

 sucking forms. 



The eggs of the Chironomidae are small and ovoid, or long and 

 pointed at their extremities, and are laid either in a gelatinous string 

 of mucus or separately. The larva usually consists of thirteen seg- 

 ments, and is eucephalic and amphipneustic ; its head is directed 

 downwards, and the mandibles are well developed. On the ventral 

 surface of the first thoracic segment, and on the extremity of the last, 



