DIPTERA. 



75 



ticks. The species known from its abundance in the New Forest as the forest-fly 

 (Hippobosca equind) has the wings well developed. It infests horses and oxen, 

 usually attaching itself to those parts of the body where the covering of hair 

 is scanty. A second kind, known as Ornithomyia avicularia, occurring, as its name 

 indicates, on birds of almost all kinds, also possesses a pair of fully developed 

 wings ; but in another species, Stenopteryx hirundinis, which is found on swallows 

 and about their nests, the wings are narrow and sickle-like and scarcely fitted for 

 flight. A fourth species, the so - called deer - tick 

 (Lipoptena cervi), is provided with wings upon issuing 

 from the pupa-case ; but after flying about for a time 

 the insects settle upon deer, and drop their wings by 

 fracturing them at the base. The last member of the 

 family to be mentioned, the so-called sheep-tick which 

 must not be confounded with the mite of that name 

 is entirely wingless from its birth. We thus get in 

 this family a series of forms starting with the fully- 

 winged forest-fly and leading through the swallow-tick 

 with its wings reduced in size, and the deer-tick which 

 can cast its wings, to the sheep-tick which has entirely 

 lost these organs. The second family of the group, 

 Nycteribiidce, contains the single genus Nycterbia, the 

 species of which live parasitically upon bats. All are wingless and have lost 

 their compound eyes, but possess the balancers. The legs are long, powerful, 

 and furnished with strong hooked claws, by means of which they cling to the 

 hosts they infest. The bee -louse (Braula caeca: G. on p. 38), the type of the 

 family Braulidce, is a minute, blind, and wingless insect infesting honey-bees; 

 being found upon the workers, as well as upon the drones and queen, but seeming 

 to have a preference for the two latter as hosts. 



COMMON FOREST-FLY (enlarged). 



THE FLEAS, Family PULICID^;, etc. 



The fleas, w r hich by some are regarded as an order (Aphaniptera), may be 

 considered to be aberrant flies ; their mouth-organs, which are adapted for piercing 

 and sucking, being modified upon the same principles as obtain in the flies. They 

 further resemble that group in undergoing a complete metamorphosis, but differ 

 from the majority of flies in being destitute of wings. The group is divisible into 

 two families. In the true fleas or Pulicidce the body of the adult is strongly flat- 

 tened from side to side, and thus, in conjunction with the smooth, hard, and nearly 

 naked integument, enables the insect to swiftly traverse the hairy coating of its host. 

 Some of the segments, however, are usually armed with strong backwardly-projecting 

 spines. There are no compound eyes, but each side of the head is furnished with a 

 simple eye ; the legs being long, strong, and fitted for leaping. The eggs are laid 

 about the floors of houses, kennels, etc. ; and the larvae, which are slender, worm- 

 like creatures, devoid of legs, but furnished with a biting mouth, live on particles of 

 decaying organic matter found in the dust of the places they infest. When adult, 

 the larva, or maggot, is said to spin a cocoon within which the pupa state is passed. 



