DIPTERA 



801 



The family includes only a single genus, Dixa, of which eight 

 species have been found in North America. 



The adult midges occur in the vicinity of streams and in swam- 

 py places. 



The larvae are aquatic, living in ponds or slowly running water; 

 they resemble somewhat those of Anopheles but the body is almost 

 alwa3'S bent so that the head and tail come close together. They 

 progress by alternate thrusts of the two ends of the body the bent 

 portion traveling foremost (Fig. 1012). The first and second ab- 

 donimal segments each bear a pair of pseudopods on the ventral 

 surface. These larvae feed on algae. 



Family PSYCHODID^ 

 The Moth-like Flies 



There may be found frequently upon windows and on the lower 

 surface of the foliage of trees small flies which have the body and 

 wings densely clothed with hair and which resemble tiny moths in 

 appearance. The wings are broad, and when at rest slope at the 

 sides in a roof-like manner or are held horizontally in such a way as 

 to give the insect a triangular outline (Fig. 10 13). 



The moth-like appearance of these insects is suffi- 

 cient to distinguish them from all other flies. The ven- 

 ation of the wings, (Fig. 10 14) is also very peculiar. 

 All of the longitudinal veins separate near the base 

 of the wing except veins R2 and R3 and veins Mi and 

 M2. In some forms veins R4 and R5 are distinct, as 

 shown in the figure, in others they coalesce complete- 

 ly, so that radius is only four-branched. Cross-veins 

 are wanting in most cases. 



The antenna are long and slender, and are clothed with whorls of 



Fig. 1 013. —A 

 m o t h -li k e 

 fly. 



Wing of a moth-like fly. 



hairs (Fig. 1015). Those of the male are longer; and in the species 

 figured the two basal segments are clothed with scales like those of 

 the Lepidoptera. Scales of this form occur also on the wings, palpi, 

 and legs of certain species. 



