624 DIPTEEA. 



Bracy Clark, Esq., wlio has published some very inter- 

 esting remarks* on the hots of horses and of other animals, 

 maintains that hots are rather beneficial than injurious to 

 the animals they infest. His principal work on this sub- 

 ject I have not yet seen. The maggots (Fig. 

 Fig. 273. 273) of the (Estrm bovis, or ox bot-fly, live 



in large open boils, sometimes called wornils 

 or wurmals, that is, worm-holes, on the backs 

 of cattle. The fly is rather smaller than the 

 horse bot-fly, although it comes from a much larger mag- 

 got. The sheep bot-fly (^Cephalemyia avis') lays its eggs 

 in the nostrils of sheep, and the maggots crawl from thence 

 into the hollows in the bones of the forehead. Deer are 

 also afflicted by bots peculiar to them. Our native hare, 

 or rabbit, as it is commonly called, sometimes has very 

 large bots, which live under the skin of his back. The 

 fly (^(Estrus hwccatus) is as big as our largest humble-bee, 

 but is not hairy. It is of a reddish-black color ; the face 

 and the sides of the hind body are covered with a bluish 

 white bloom ; there are many small black dots on the lat- 

 ter, and six or eight on the face. This fly measures seven 

 eighths of an inch or more in length, and its wings ex- 

 pand about three quarters of an inch. It is rarely seen ; 

 and my only specimen was taken in the month of July, 

 many years ago. 



At the very end of this order is to be placed a remarkable 

 group of insects, which seems to connect the flies with the 

 true ticks and spiders. Some of these insects have wings ; 

 but others have neither wings nor poisers. Of the winged 

 kinds there is one (^Hippohosca equina) that nestles in the 

 hair of the horse ; others are bird-flies ( Ontithomyia), and 

 live in the plumage of almost all kinds of birds. The ^ving- 



* " Observations on the Genus CEstnis," in the Transactions of the Linnsean 

 Society, Vol. III. p. 289, witli figures; " On the Insect called Oistros by the An- 

 cients," in Vol. XV. of the same work; and "An Essay on the Bots of Horses and 

 other Animals," 1 vol. 4to (Lond., 1815). 



