PUPIPAEA. 



97 



cavities, where they adhere to the mucous membranes by means of the hooks with which their 

 mouths are provided. The larva of the best-known species (Cephalomyia ovis) infests the Sheep, 

 and is described as sometimes making its way into the brain, and causing vertigo and finally 

 the death of the animal. The Sheep show their recognition of their enemy very plainly when the 

 fiy comes near them, by shaking their heads and stamping on the ground, or, as a last resource, 

 getting into dry, dusty spots, and crowding together with their noses to the ground. The larvae, 

 when full grown, escape again through the nostrils, and fall to the ground, where they become 

 pupae. A large species (C. auribarbis), which is parasitic on the Red Deer in Germany, is. 

 described as shooting its young larvae into the nostrils of its victim 

 without alighting. The Reindeer has also its peculiar plague of this kind 

 (C. trompe). 



The larvae of the species of Gastrus or Gasterophilus harbour in the 

 stomachs of various herbivorous mammals, but especially of Horses, in 

 which they are well known as "bots." The female of course is unable 

 to introduce her offspring directly into the stomach of the animal on 

 which it is to be parasitic, but she attaches her eggs to the hairs of those 

 parts which are easily reached by the tongue, and indeed are habitually licked. 

 The warmth and moisture of the tongue speedily hatch the eggs, and the 

 parasitic larvae, by adhering to the organ, are conveyed into the mouth of 



the victim, whence they easily make their way into the stomach. Here they adhere to the mucous, 

 membrane by means of the mouth-hooks, and their presence in any number is by no means 

 advantageous to their host. The best-known species is the Gastrus equi. Another (G. Iwemorrhoidalis} 

 goes directly to the lips of the Horses for" the purpose of depositing its eggs. G. elephantis inhabits, 

 the stomach of the Elephant. 



TRIBE V. PUPIPARA. 



This last tribe of the Diptera consists of a comparatively small number of exceedingly curious, 

 creatures which are persistently parasitic in their perfect state, which, however, in this case 

 means throughout the whole of their active lives, seeing that the eggs are hatched and the 



larvae retained and nourished within the body of the mother 

 until they have arrived at maturity, when they are extruded 

 and immediately pass to the pupa state. Only a single larva 

 is developed at a time. From the structure of the ovaries- 

 S) they cannot be very prolific. 



GASTRUS EQUI. 



FAMILY XXI. HIPPOBOSCID^E. 



In this family wings and halteres are generally present, 

 though the insects do not seem to have much occasion for 



O 



such organs, as they live parasitically upon the bodies of birds 



Ill 



and mammals. They have a hard, depressed body ; the head 

 is placed horizontally, and bears large eyes ; the antennae are very short ; the proboscis consists of 

 the maxillae and labrum alone, the labium being abbreviated ; and the legs are articulated at the 

 sides of a very broad pectoral plate, so that in some cases 

 they seem to spring from the sides of the body. The 

 wings are usually distinctly veined only towards the fore 

 margin ; they are sometimes deciduous, and sometimes 

 altogether wanting ; the halteres are small, free, and placed 

 low down ; and the tarsi have very strong bifid claws. 



Hippobosca equina, the type of this family, is parasitic 

 upon Horses ; it is well known in the New Forest under 

 MELOPHAGUS ovtNus. the name of the Forest Fly. The Sheep Tick (Melophagus 

 ovinus) is another well-known species ; it has no wings, 



and the abdomen is widened posteriorly. The genus Lipoptena is peculiar in that the wings are 

 deciduous ; and singularly enough, in some cases at any rate, the winged individuals are found on 

 251 



LIPOPTENA CEKVI. 



