GAD-FLY. 
456 
been accurately related by the ingenious Mr. Bracy 
Clark, from whose paper we have taken the liberty 
to extract the following particulars : 
« When the female has been impregnated, and 
the eggs are sufficiently mature, she seeks among 
the horses a subject for her purpose; and approach- 
ing it on the wing, she holds her body nearly up- 
right in the air, and her tail, which is lengthened 
for the purpose, curved inwards and upwards : in 
this way she approaches the part where she designs 
to deposit her egg ; and, suspending herself for a 
few seconds before it, suddenly darts upon it, and 
leaves her egg adhering to the hair : she hardly ap- 
pears to settle, but merely touches the hair with 
the egg held out on the projected point of the ab- 
domen. The egg is made to adhere by means of a 
glutinous liquor secreted with it. She then leaves 
the horse at a small distance, and prepares a second 
egg, and, poising herself before the part, deposits it 
in the same way. The liquor dries, and the egg 
becomes firmly glued to the hair : this is repeated 
by various flies, till four or five hundred eggs are 
sometimes placed on one horse. The horses, when 
they become used to this fly, and find that it does 
them no injury, as the Tabani and Conopes , by suck- 
ing their blood, hardly regard it, and do not appear 
at all aware of its insidious object. The skin of 
the horse is always thrown into a tremulous motion 
on the touch of this insect, which merely arises 
from the very great irritability of the skin and cu- 
