ox GAD FLY. 301 
the eggs slide down into the wound. 
There the warmth of the beast soon 
hatches them, and the larvae, or worms, 
feed on the matter produced by the 
sore. 
Lucy What odious little creatures ! 
But do not they hurt the cows most 
dreadfully ? 
Mother, At the moment of boring 
the hole, and inserting the eggs, the cat- 
tle seem to suffer very much ; but after- 
wards the tumours they create do not, 
as far as we can judge, occasion any se- 
rious pain: I have even heard, that in 
Norfolk, and Suffolk, they are reckoned 
useful ; and that, as the oestrus selects the 
healthiest cattle, the farmers prefer those 
cows, which have on their back three or 
four of the lumps, or hots, produced by 
this insect. The cattle are, however, 
thrown into the greatest agitation and 
distress at the sound of its well-known 
buz; they run about the field, lashing 
their tails, and bellowing with apprehen- 
