HIPPOBOSCIDAE 



519 



Hippoboscidae live on birds, and are apparently specially fond of 

 the Swallow tribe. They are all winged, though in some species 

 the wings are very small. The bird- 

 infesting Hippoboscidae have been very 

 little studied, and will probably form a 

 distinct family ; the antennae of Sten- 

 opteryx hirundinis are quite different 

 from those of Hippobosca. The devel- 

 opment is remarkable, and has been 

 studied by Leuckart l and by Pratt 2 in 

 the case of Melophagus ovinus. The 

 ovaries are peculiarly formed, and pro- 

 duce one large egg at a time ; this 

 passes into the dilated oviduct, and there 

 goes through its full growth and a cer- 

 tain amount of development ; it is then 

 extruded, and undergoing little or no 

 change of form becomes externally 

 hardened by the excretion of chitin, 

 passing thus into the condition of the 

 Eumyiid pupa. Dufour thought that 

 there is no larval stage in this Insect, 

 but it is quite clear from later researches 

 that he was wrong, and that a larval 

 stage of a peculiar kind, but in some re- 

 spects resembling that of the Eumyiid 

 Muscidae, occurs. The larva has no 

 true head, but the anterior part of the 

 body is invaginated, and the most 

 anterior part again protrudes in the 



invagination, so that two little passages appear on section (Fig. 

 246) ; the upper one leads to the stomach, which is of very 

 large size. The tracheal system is peculiar ; it is metapneustic, 

 there being neither anterior nor lateral spiracles. Pratt says 

 that there is at first a single pair of terminal spiracles, and sub- 

 sequently three pairs, hence he considers that the terminal part 

 of the body corresponds to three segments. This is however 

 probably a mistaken view ; it appears more probable that the so- 

 called three pairs of stigmata really correspond with the complex 

 1 AWi. Ges. Halle, iv. 1858, p. 145. 2 Arch. Naturgesch. lix. i. 1893, p. 151. 



P 



FIG. 246. Diagrammatic section 

 of the larva of Melophagus 

 ovinus. (After Pratt.) a, 

 mouth ; b, suctorial pouch ; 

 c, imaginal disc for adult 

 head ; d, meso- and meta- 

 notal discs, e, anterior trach- 

 eal anastomosis ; /, first 

 muscular belt ; g, transverse 

 tracheal branch ; /t, the dorsal 

 tracheal tube ; i, sex-organ ; 

 k, Malpighian tube ; I, ter- 

 minal part of intestine ; m, 

 terminal chamber of tracheal 

 tube ; n, stigmatic fossa ; o, 

 terminal part of intestine ; p, 

 anus ; q, anal disc ; r, ventral 

 tracheal tube ; s, stomach ; 

 t, nervous system ; it, discs 

 for the three pairs of legs of 

 the imago ; v, ventral pouch ; 

 w, pharynx ; x, suctorial lip. 



