41 8 ARTICULATES : INSECTS. 



two hooks, and the segments of the body are also armed 

 with hooks or prickles. More than twenty species are 

 known, and several are found in this country. 



The Genus Gasterophilus comprises three species, which 

 Fig 307 infest the horse. The Large Bot-Fly, 



G. equi, Linn., lays her eggs upon the 

 fore legs of the horse ; the Red-tailed 

 Bot-Fly, G. hcemorrlioidalis, Linn., 

 lays her eggs upon the lips ; and the 

 Brown Farrier Bot-Fly, G. veterinus, 



Bot-Fly, G. egui, Linn. Q reen> under the ^ Q ^ By biting 



the parts where the eggs are laid, the horse gets the larvae 

 into his mouth, swallows them, and, clinging to the walls 

 of the stomach, they remain there till fully grown. 



The Genus CEstnis contains the Ox Bot-Fly, O. bovis, 

 Fabr., which deposits her eggs in the skin of the backs of 

 cattle, and the larvae live in large open sores. 



The Genus Cephalemyia contains the Sheep Bot-Fly, 

 C. ovis, Linn., which lays its eggs in the nostrils of sheep, 

 and the larvae crawl into the cavities in the bones of the 

 forehead, and in many cases produce death. 



MUSCIM:, Latr., OR FLY FAMILY. This Family com- 

 prises diptera which have short antennae that end with 

 an oval joint and a lateral bristle, a short, soft proboscis 

 ending with large fleshy lips, enclosing a sucker com- 

 posed of only two bristles, and capable of being entirely 

 retracted into the oral cavity. The larvae are fleshy, 

 whitish maggots, and never cast their skins ; but when 

 they pass to the pupa state, they shorten, become oblong- 

 oval, dry, hard, and brown on the outside. This family 

 includes about one third of all the Diptera, and its mem- 

 bers are known under the names of House-Flies, Blow- 

 Flies, Flesh-Flies, Flower- and Fruit-Flies, Cheese-Flies, 

 &c. Meisren has described about seventeen hundred Ku- 



o 



ropean species. 



