72 
INSECTS. 
infected fruit drops to the ground, and the larvae when mature pass out to become 
pupae beneath the earth. Besides oranges and other acid fruits, peaches and 
melons are attacked by this fly. The annexed figure represents another of these 
injurious little insects ( Chlorops tceniopus), a shining yellow fly variegated with 
black bands. This species and its allies, which are most 
destructive in the larval stage to cereals and grass, 
much resemble in the cycle of their development the 
above-mentioned Hessian fly. Allied to the preceding in 
structure and habits are the members of the sub-family 
Ortalince, containing the genus Ortalis and others. A 
curious representative from the Malay Archipelago, 
known as the staghorn-fly ( Elaphomyia ), takes its name 
from the development of the sides of the head into 
large branching horns. This, however, is only a sexual character, and confined to 
the male. Finally, the small black fly ( Piophilct easel), known in the grub-stage 
as the cheese-hopper, belongs to that group of Museidee in which there are no 
scales to cover the balancers. 
Chlorops tceniopus, with figure 
showing side view of head 
(much enlarged). 
Gad-Flies and Bot-Flies,—F amily CEsteid^e. 
The flies of this family are mostly of large size, and many present superficial 
resemblance to various kinds of bees. In structural characters they are nearly 
allied to house-flies, but the head is larger and broader and the mouth-parts are 
reduced. In the larval stage gad-flies infest, either 
as internal or external parasites, various mammals, 
but since those that attack domestic cattle have 
been more thoroughly studied than the others, 
attention will mainly be directed to three of the 
best known forms, namely, those that infest respect¬ 
ively horses, oxen, and sheep. The horse bot-fly 
(Gastrophilus equi), which resembles the honey¬ 
bee in size, colour, and form, lays its eggs on the 
skin of horses, asses, and mules, which seem to 
have an instinctive dread of the insect. It has 
been noticed, moreover, that the gad-fly instinctively 
selects for the purpose a spot that is well within 
reach of the quadruped’s mouth. The reason for 
this, although not at first very obvious, becomes 
clear when it is understood that the larval fly can 
only obtain its proper nourishment in the alimentary 
canal of its host. As soon as the maggot emerges 
from the egg it starts to irritate the horse’s skin. 
Thereupon the horse, to remove the irritation, licks 
the infested spot and swallows the maggots, which 
then attach themselves by means of their hook-like , Adu !!** , t0 * ‘f = 
^ 1 c , Mature larva ; a, Newly-hatched 
mandibles to the inner wall of the stomach or larva ; e, Pupa. (All enlarged.) 
