FLIES. 239 



snails and insects, or on decaying vegetable matter, such as fungi 

 or potatoes. 



These flies are of small or moderate size, and are generally of 

 a black or rusty yellow colour. They are very active, and may be 

 observed on plants, and less frequently on windows. 



DlPTERA HOMALOPTERA. 



The insects belonging to this section much resemble spiders by 

 their hairy sprawling legs and general appearance. They are all 

 parasitic, and are remarkable for the perfect insect producing its 

 young singly, and that not in the egg state, as in most other 

 insects, but either in the pupa state, or as a mature larva, ready to 

 become a pupa immediately. 



FAMILY XXKYLLHippoboscidce. 



Body horny and flattened ; antennae composed of one joint 

 only, and furnished with a terminal bristle ; eyes and ocelli large or 

 small, or absent ; abdomen often very broad ; legs short and strong. 



Several interesting insects are comprised in this family. The 

 first is the Forest Fly (Hippobosca Equina, Linn.), a brown species, 

 about one-third of an inch in length, which attacks the horse, and 

 is exceedingly annoying to the animal, but more from the irrita- 

 tion it produces by creeping about under the belly than by the 

 actual puncture which it inflicts to suck the blood. The deer and 

 the camel are likewise subject to the attacks of similar parasites. 



The species of Ornithomyia, Latr., infest birds, living beneath the 

 feathers. They are of a .yellowish or greenish colour, and are about 

 half the size of Hippobosca. 



The preceding species are all winged, but every one who has 

 ever seen a sheep-shearing must have seen a brown wingless insect 

 rather less than a quarter of an inch in length among the freshly- 

 clipped wool. This is Melophagus Ovinus, Linn., and is generally, 

 but improperly, called the sheep-tick in England. In this species 

 the eyes are very small, and the ocelli are wanting. 



The genus Braula, Nitsch, is considered by some writers to 

 belong to this family, while others regard it as forming a family 

 by itself. The only species (B. Caeca, Nitsch) is a very small, 

 blind, and wingless reddish-brown insect, parasitic upon the hive- 

 bee, and known as the bee-louse. It is not exactly pupivorous, 

 but the larva assumes the pupa state very shortly after quitting 

 the egg. 



