TIPULIDAE 



473 



suture of the inesonotum is indistinct ; the larvae are aquatic and 

 have the head free, the terminal two segments 

 of the body enormously prolonged (Fig. 223), 

 forming a long tail bearing, in the Xorth 

 American Bittacomorplia, two respiratory fila- 

 ments. Hart l describes this tail as possessing 

 a stigmatal opening at the extremity ; no doubt 

 the structure is a compounded pair of spiracles. 

 The pupa (Fig. 223, B) has quite lost the respira- 

 tory tube at the posterior extremity of the 

 body, but has instead quite as long a one at 

 the anterior extremity, due to one tube of the 

 pair normal in Tipulidae being enormously 

 developed, while its fellow remains small. This 

 is a most curious departure from the bilateral 

 symmetry that is so constantly exhibited in 

 Insect-structure. Our British species of Ptych- 

 optera have the pupal respiratory tube as extra- 

 ordinary as it is in jBittacomorpha, though the 

 larval tail is less peculiar. 2 This group should 

 perhaps be distinguished from the Tipulidae 

 as a separate family, but taxonomists are not 

 yet unanimous as to this. Brauer considers 

 that the head of the larva, and the condition 

 of five Malpighian tubules in the imago, 

 require the association of Ptychopterinae with 

 the preceding families (Chirouomidae, etc.), 

 rather than with the Tipulidae. 



The great majority of the Tipulidae are com- 

 prised in the sub-family Limnobiinae the 

 Tipulidae Brevipalpi of Osten Sacken : 3 in 

 them the last joint of the palpi is shorter or FIG. 223. Bittaco- 

 not much longer than the two preceding 

 together. They exhibit great variety, and many 

 of them are types of fragility. The common 

 winter gnats of the genus Trichocera are a 

 fair sample of this sub-family. The species 

 of this genus mostly inhabit high latitudes, and delight in 



morpha davipes. 

 North America x \. 

 (After Hart.) A, 

 Larva ; B, pupa : 

 I, the left, r, the 

 right respiratory 

 tube. 



Bull. Illinois Lab., iv. 1895, p. 193. - M lull's Aquatic Insects, 1895, p. 174. 



3 "Studies," etc., Berlin, ent. Zeitschr. xxxi. 1887. 



