DIPTERA. 
75 
ticks. The species known from its abundance in the New Forest as the forest-fly 
(.Hippobosca equina) 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 liirundinis, 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 j 
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, C0MM0N F0EEST . FLY (enlarged). 
JPycteribiidce, 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 cceca; 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. 
The Fleas,—F amily Pulicidje, etc. 
The fleas, which 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. A\ hen adult, 
the larva, or maggot, is said to spin a cocoon within which the pupa state is passed. 
