454 
GAD-FLY. 
the direction of the spine, and the head and neck 
are also stretched out to the utmost. The horror 
excited by these insects in cattle is so great that 
nothing will prevent their efforts to escape from 
them. This is well known to those farmers who 
employ oxen to plough their lands, many of them 
having a contrivance to set the beasts at liberty the 
moment they are bitten : where this precaution is 
neglected, unpleasant consequences sometimes en- 
sue ; as the oxen become quite furious upon these 
occasions, and will frequently run with the plough 
directly forwards, through hedges, or whatever ob- 
structs their way. 
We have already noticed that each puncture 
made by the gad-fly is followed by an egg, which 
after a time is hatched in the back of the animal, 
and the larva, by the irritation it produces, causes a 
swelling in the part, which terminates in a small 
abscess open at the top. The young maggot is im- 
bedded in the fluid of this abscess, where it con- 
tinues all the winter, and in the following June 
forces its way through the opening, and, falling from 
the back of the animal to the ground, becomes a chry- 
salis. At this time, we are told, the maggot is in great 
danger of being destroyed ; for if it falls on land it is 
frequently trodden upon, or picked up by birds ; if 
it falls in the water, where the cattle stand during 
most of the day in the summer season, its fate is 
certainly decided, as it either perishes, or becomes 
the food of fishes. After the larva is excluded, the 
sore upon the back of the animal soon heals. 
