DIPTERA. 117 



and become pnpoe. These larvfe do not make their way 

 to the brain and cause the death of the poor sheep, as is 

 often asserted. Sheep may often be seen in hot weather 

 shaking their heads and holding their noses close to the 

 ground in dry dusty spots, in order to prevent the gad- 

 fly entering the nostrils. 



The Horse Bot-fly {Gasterophihis equi) deposits its 

 eggs on the hairs of such parts of the body as the horse 

 can reach with its tongue ; these parts being licked by 

 the horse, the attached eggs — little yellow specs, familiar 

 to all — are conveyed to the stomadh, where the larvae 

 are developed ; when full grown the larva detaches 

 itself and discharged by the horse falls to the ground, 

 where the final changes are undergone. It is curious 

 to see this Bot-fly in the act of laying its eggs on the 

 horse's skin ; it will remain for a few seconds opposite 

 a spot in the horse, hawk-like — the wings vibrating with 

 amazing rapidity — and then, with its pointed abdomen, 

 afiix an egg to the hair ; then the process will ba re- 

 peated. 



The sub-section — Hypocera — in which the antennae 

 are situated low down near the mouth, consists of the 

 genus Phora only, which contains a few minute flies, 

 which need not detain us at all. 



The Eproboscidea, the second section of the Diptera, 

 contain insects which are parasitic in various quadrupeds 

 and birds, such as the Forest-fly {Hippobosca), the 

 Sheep-tick {Melophagus ovitms), the Bird-tick {Ornitho- 

 myia avicularia), the Swallow-tick {Stenopterix Hirun- 

 dinis), and the Bat-tick (Xi/cterihia). 



