24 THE EARLY STAGES OF TABANID^ 



such has a chitinous lining. Graber believed that the structure is 

 an auditory organ, but Lecaillon supposed it to be a gland. Berlese, 

 according to Patton and Cragg, does not consider that it has been 

 proved to be a sense organ, though it is well supplied with nerves. 

 Paoli has shown that the young larva has only two pedunculate 

 bodies, and that with each successive molt a new capsule with two 

 more such bodies is formed. Having observed that Tahanus larvae 

 are able to produce a slight crackling noise, Paoli believes the struc- 

 ture to be a sound-producing organ, but it is dilfhcult to understand 

 what ecological meaning such an organ could have.* 



The pupae of tabanids are classified as orthorhaphous (Brauer), 

 opening in the act of hatching with a dorsal longitudinal slit. They 

 strongly resemble lepidopterous pupae {Mumienpuppe, pupa obtecta), 

 having wing and leg cases firmly attached to the body and covered 

 with it by a chitinous membrane. The pupal body is subcylindric, 

 abruptly pointed or rounded anteriorly, and tapering somewhat poste- 

 riorly; it is generally yellowish brown to ferruginous brown, finely 

 wrinkled, and has a lateral tuft of hairs on each abdominal segment. 

 On either side of the head are the antennal sheaths, pointing outwards, 

 and on each side of the median line two large tubercles, each with a 

 central hair; below these are two raised areas with sharp edges, sepa- 

 rated by a deep ridge. Lower still there is a pair of elevations, also 

 with raised edges, and on the ventral surface of the head one or more 

 tubercles. The segments of the thorax are indistinct; the mesothorax 

 bears the large raised ear-shaped spiracles. The abdominal seg- 

 ments are free and about equal in length, and have one or more fringes 

 of hairs near their hind margins; the second to the seventh segments 

 inclusive have well marked lateral areas, covered with long hairs 

 which are continued into the dorsal and ventral surfaces and corre- 

 spond to the lateral areas in the larval integument. These hairs in- 

 crease in length from before backwards, and are best developed on the 

 seventh segment. The eighth segment is short, and is provided with 

 six projecting spurs or teeth, and with a large anal tubercle. In the 

 male the tubercle is ribbed and bounded anteriorly by a continuous 

 fringe of strong spines; in the female the tubercle is smaller and the 



* For details concerning the structure of this organ, refer to pp. 29-43. 



