154 Flies [CH. 
the horse’s mouth and thence into the stomach. They 
do not necessarily get into the horse on which the eggs 
are laid, as another horse may lick the eggs and swallow 
the maggots. In the stomach the young larvae 
attach themselves to the wall by means of a pair of 
strong hook-like jaws. They are enabled to move 
through the contents of the stomach by means of 
transverse rows of curved spines pointing backward 
situated at the juncture of the segments except at the 
posterior end. The bots feed on the products of 
inflammation which they set up. They may remain 
fastened to the stomach wall for nearly a year when 
they drop off and pass to the exterior in the faeces. 
When fully grown they may reach about 1 inch in 
length. They are somewhat pointed in front, but end 
bluntly at the hind end which carries a large compound 
spiracle. This can be closed by means of a pair of 
fleshy lobes which prevent the bots from becoming 
choked. 
If they fall on suitable ground they burrow into it 
to change into puparia. This usually takes place in 
June and the flies come out a few weeks later. There 
are several different species of bots in addition to the 
one described above, one of which attaches itself to 
the anus of the horse. Bots have also been found in 
the brain and spinal cord. 
Remedial Measures. 
Like the warble fly this fly does not like shade and 
hence plenty of shelter should be provided in the 
fields. Well groomed horses rarely suffer from bots, 
as the eggs are brushed off. 
