TRACHEATA 375 



Gastrophilus equi, the horse-bot, lays its eggs on the hairs 

 of the hips and legs, the horse licks these off, and the larvae 

 hatch out in its stomach ; the larvae are found from May to 

 October hanging in clusters on the wall of the rectum. Hypo- 

 derma hovis, the ox-bot, deposits its egg beneath the skin of 

 cattle; the larvae hatch out, and cause large hollow cysts to 

 form around them ; they lie in these cysts with their stigmatic 

 plate directed to the opening. Oestrus ovis, the sheep-bot, is 

 said to be viviparous: the female deposits larvae alive in the 

 nostril of the sheep, whence they make their way to the frontal 

 sinuses. 



Family Muscidae. — This family, which is very extensive, 

 includes the common house-iiy and blue-bottle fly, etc. The 

 antennae are three-jointed, and end in a bristle. The proboscis 

 terminates in a fleshy bilobed process. The 

 wings have four simple longitudinal veins. 

 The abdomen has only flve segments visible 

 externally, but others are invaginated. The 

 larvae are white, cylindrical, apodal maggots, 

 with a posterior pair of spiracles, and some- 

 times a prothoracic pair as well. 



Musca domestica and M. vomitoria are the 

 house and blue-bottle flies. The tsetse fly, 

 which is so poisonous to cattle in South Fig. 211.— oiossinia 

 Africa, is Glossinia morsitans. The Tachin- tsr-fly""* ^ ^^' 

 idae lay their eggs in caterpillars, within 

 whose body their larvae are parasitic. Several species are 

 stated to be viviparous. 



Okdee 8. HYMENOPTERA. 



Characteristics. — Insects with biting and licking mouth ap- 

 pendages. The prothorax is fused with the mesothorax. 

 The four wings are memlranous, with few nervures, the 

 hind wing on each side bears a row of hooks, by means of 

 which it is hooked to the anterior wing, and the two move 

 together. The metamorphosis is complete. 

 The Hymenoptera include the ants, bees, and wasps, 



insects which, with regard to their social habits and instincts, 



