270 SANITARY ENTOMOLOGY 



sparse hairs. The abdomen is rather long, the tracheal tubes are broad, 

 band-shaped. The air-tube is stout, short, strongly tapered on outer 

 half, over twice as long as wide, with the pecten running nearl}' halfway, 

 followed by a single tuft of a few hairs. Each single pecten-tooth is a 

 ratlier long spine with two large and some small teeth witliin and small 

 ones without. The lateral comb of tlie eighth segment is composed of 

 ten scales in a single row. The anal segment is short, wider than long, 

 almost ringed by the plate, which nearly touches vent rally, but is not 

 united. The ventral brush is moderate, directed posteriorly. The anal 

 gills are long, wide, tracheate, with rounded tips. 



The larvae live in accumulations of water in artificial receptacles. 

 Originally it was a tree-hole-inhabiting species, but is now wholly domesti- 

 cated and is found in houses and in the vicinity of human habitations. 

 The larvag thrive very well in water containing food refuse and in 

 muddy water. 



Culex quinquefasciatus larva (see fig. 48) has the head rounded, 

 widest through the e^'es. The thorax is rounded, wider than long. The 

 abdomen is moderate, with the anterior segments shorter. The tracheae 

 are rather broad. The air tube is rather stout, tapered on outer half, 

 four times as long as wide, with the pecten running about one-third, each 

 pecten-tooth is broad with three to six branches. The lateral comb of 

 the eighth segment is composed of many spines in a triangular patch. 

 The anal segment is a little longer than Avide, ringed by tlie plate. The 

 ventral brush is well developed, confined to the barred area. The anal 

 gills are rather short and broad, longer than the segment, tapered 

 toward tips. 



The larvae are found most frequently in artificial receptacles, but 

 also in ground pools in the vicinity of habitations when the water is 

 sufficiently polluted. The species thrives best in water charged with 

 animal matter and shows a preference for filthy water. Breeding goes on 

 continuously while conditions are favorable. Under the most favorable 

 conditions the larval period may be five or six days. 



Anopheles crucians larva has the head rounded, elongate, bulging at 

 the sides, with the frontal portion before the antennae conicalh^ produced. 

 The thorax is rounded quadrate, about as long as wide. The abdomen 

 is stout, with the anterior segments shorter. Tlie air tube is sessile, sub- 

 quadrate, roundedly angled posteriorly. The lateral plates of the eighth 

 segment are posteriorly armed with a series of about eight long, stout 

 spines, separated from each other by from one to four short spines. The 

 anal segment is about as long as wide, with a small dorsal plate. The 

 ventral brush is well developed, of long branched tufts. The anal gills 

 are moderate, about as the segment, slightly constricted centrally, blunt 

 pointed. 



