&J 



Family 

 HIPPOBOSCID^. 



The strange-looking flies composing this Family are parasitic 

 upon mammals and birds, and are probably descended from 

 ancestors belonging to the Muscid;E, which underwent modification 

 in bodily structure as a consequence of the adoption of a parasitic 

 mode of life. The body in all cases is flattened and horny ; the feet 

 are provided with accessory claws to enable the insect to cling to 

 the hair or feathers of the host ; and while some of the forms, such 

 as the Forest Fly (Plate 31), and Ornithoviyia avicularia, Linn. 

 (Plate 32) are fully-winged, others show a progressive reduction in 

 this respect until in the " Sheep Tick " {Melophagiis oviniis, Linn., 

 Plate 34), the wings are wanting altogether. But even in fully- 

 winged forms, since the flies are true parasites, the wings, as a rule, 

 are made use of merely in order to reach the host, or, in the case of 

 the males, in order to find an indi\ iflual of the opposite sex, and 

 thereafter it is only in exceptional circumstances, such as the death 

 of the host, or too acti\-e pursuit b_\- the human hand, or when taking 

 a short flight from one animal to another, that these flies are ever 

 seen upon the wing. The proboscis in the Hippoboscida; is curved, 

 extremely slender, and protrusible, but is composed of the same 

 parts as that of the blood-sucking Muscida;. In appearance it 

 presents a decided resemblance to the proboscis of the Tsetse-flies, 

 and it also acts in the same way as the latter, its tip being armed 

 with sharp chitinous teeth which enable the organ to pierce the skin 

 of the host. Another point of resemblance to the Tsetse-flics is to be 

 found in the mode of reproduction, which is a further development 

 of the process seen in the flies referred to, and has caused the 

 Hippoboscida: and certain other families of parasitic Di])tera 

 belonging to the same group to receive the name Piipipara. Li these 

 forms, namely, the pregnant female does not lay eggs, but produces 

 at each birth a full-grown larva, which assumes the pupal state 

 iinmediatcl}' after extrusion. 



In addition to those figured in Plates 31 to 34, the fauna of the 



