156 BOTS. 
ground, his fore legs, or sometimes against a tree, with great emotion; 
till the animal at length finding this mode of defense insufficient, enraged 
he quits the spot, and endeavors to avoid it by galloping away to a 
distant part of the field; and if the fly still continues to follow and tease 
him, his last resource is in the water, where the estrus never is observed 
to pursue him. These flies appear sometimes to hide themselves in the 
grass ; and as the horse stoops to graze, they dart on the mouth or lips, 
and are always observed to poise themselves during a few seconds in the 
air, while the egg is preparing on the extended point of the abdomen. 
THE ESTRUS HEMORRHOIDALIS. 
Copied from the Work by Bracy Clark, Esq. 
1. The female fly about to deposit an egg. 3. The bot. 
2. The egg, magnified. 4, The chrysalis. 
5. The male fly. 
“When several of these flies are confined in a close place, they have a 
particularly strong, musty smell; and I have observed both sheep and 
horses, when teased by them, to look into the grass and smell it very 
anxiously ; and if they by these means discover the fly, they immediately 
turn aside and hasten to a distant part of the field. 
“‘T once saw in a meadow or field upon the cliffs at Margate, a fly of 
this sort teasing a horse that was confined to a small space by a spike 
stuck in the ground, to which a cord was tied. He could not get away 
from its attack, and became quite furious, for in kicking at the fly with 
his fore foot, which he did vehemently, he often struck the bone of the 
lower jaw, creating excessive pain; for in that direction while grazing, 
the fly comes to the beard of the lower lip. 
