VII 



TIPULIDAE 



473 



r 



suture of the mesonotmu 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 hearing, in the North 

 American Bittacomorpha, two respiratory h' la- 

 ments. Hart * 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 Ptycli- 

 optera have the pupal respiratory tube as extra- 

 ordinary as it is in BUtacomorpha, though the 

 larval tail is less peculiar. 2 This group should 

 perhaps be distinguished from the Tipulidae 

 as a separate family, but taxonornists 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 Ftychopterinae with 

 the preceding families (Chironomidae, etc.), 

 rather than with the Tipulidae. 



The great majority of the Tipulidae are com- 

 prised in the suit-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 TricJ/ocera 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 j. 

 (After Hart.) A, 

 Larva ; B, pupa : 



/, the left, /, the 

 right respiratory 

 tube. 



1 Bull. Illiiwis Lab., iv. 1895, p. 193. " ^Hall's Aquatic Insects, 1895, p. 174. 



3 "Studies," etc., L'crlin. cut. Zcitschr. xxxi. 1887. 



