CHAPTER VII 



Nematocera {continued) : Harmless Nematocera 



The eight remaining families of Nematocera are not of any particular 

 interest from the medical standpoint, but the medical officer should be 

 able severally to distinguish them as there are many species among them 

 that might be confused with mosquitoes. They are here styled harmless, 

 since they do not suck blood, but many of the species are hurtful to 

 agriculture. 



Family TlPULlD^E ; Crane-flies or Daddy-longlegs (Lat. iippula 

 = a light, long-legged insect). 



This family, which is represented in all parts of the world, includes a 

 great many species, some of them being the largest of all Nematocera 

 and the longest of all Diptera. In the great majority there is an open 

 V-shaped suture across the scutum in front of the wings, and a discal 

 cell in the wing. The legs are remarkably long and delicate, the 

 genitalia are prominent, and the proboscis in some species is elongated. 

 Some of the smaller species dance in the air in swarms like gnats. The 

 larva has a distinct head with antennae that usually are minute, and well- 

 formed mandibles and maxillae ; on the ventral surface of some of the 

 segments of the body there are small bristly tubercles for locomotion. 

 The larvae of most species live in the earth or in rotting wood, but some 

 live on the leaves of plants, and, being coloured green, resemble cater- 

 pillars, and some are aquatic and have a long contractile breathing-tube 

 at the end of the body. The pupae have slender thoracic breathing- 

 tubes one of which in some aquatic forms is of prodigious length. A 

 few species of Tipulidce are wingless. 



Family DlxiD^ (Gr. Sifos = of doubtful position). 



This family, which is supposed to connect the Tipulida with the 

 Culicida, contains one genus Dixa, the species of which are very widely 

 distributed. The adult is very much like a mosquito, but can be dis- 

 tinguished by the short proboscis, the absence of a "wing-fringe" of 

 scales, and the curious course of the 2nd longitudinal vein, which arches 

 forward, at the point of origin of the 3rd longitudinal, in such a way that 

 its proximal part appears to belong to the latter. The larva (Fig. 34) 



