GAD-FLY. 
453 
whole herd will run away in the greatest conster- 
nation, and escape, if possible, into some water, 
where they are secure from its attacks. This pre- 
caution seems implanted in them by Nature; as 
young and old, those who have suffered from the 
enemy and those who have not, fly equally to the 
only place of refuge afforded them. Their fears are 
not without foundation, since these flies are con- 
stantly upon the watch to deposit their eggs in the 
backs of the cattle ; and they are provided with a 
very curious instrument for this purpose. It con- 
sists of a cylindrical tube, composed of four pieces 
which draw out from the posterior part of the ani- 
mal like the same contrivance in a pocket telescope. 
The last of these pieces is armed with three hooks, 
and acts as a gimlet to bore through the tough 
hide, in order to make a hole for the egg which is 
to follow. This operation is performed by the fe- 
male gad-fly in a few seconds, and is generally re- 
peated on several parts of the animal’s back. Mr. 
Bracy Clark, whose observations on this genus 
of insects do him so much credit, says, that 
this species in particular inflicts the most pain 
while laying its eggs. The unfortunate beast who 
is attacked by one of these plagues may be readily 
distinguished by his agitation. He feels the wound, 
is conscious of its consequences, and in extreme 
terror runs bellowing from the rest of the herd to 
a distant part of the heath, or the nearest water ; 
while the tail, from the severity of the pain, is held 
with a tremulous motion straight from the body, in 
