7 
writers; there the barrel or tun-shaped chrysalids are 
known scientifically as tun or “ tonne ” pupae, and, if 
you look at the barrel or butt-like shape of these Bot 
Fly maggots, especially when they are hooped round 
with their dark rings, it suggests that here we have 
similarly, and with a very slight alteration of the word, 
barrel or butt, or “Bot” maggots (see pp. 11 and 20). 
However this may be, the idea will serve to keep the 
two great distinctions between the “Gad Flies” and the 
“Bot Flies” clearly before us. 
The family of the CEstridce , or Bot Flies, may be de¬ 
scribed for common purposes as consisting of good-sized 
hairy Flies, varying from about three-quarters of an 
inch to over an inch in the spread of their wings. The 
abdomen is often gaily banded with black and white, and 
yellow or orange-red. The Common Bot Fly of the 
horse is sometimes known as the “ Horse Bee,” and 
altogether, from the hairs and colouring, many of them 
are not unlike a light-made Humble Bee, excepting in 
the horns being very short, the wing-nerves few; and 
also in the female being sometimes distinguishable by 
the prolonged end of the tail, furnished with a tube for 
egg-laying, which can be (at least in the case of the 
Bein-cleer Bot Fly) lengthened or drawn in at pleasure. 
These Flies have, with few exceptions, the mouth 
obsolete, a marked distinction; and, as far as I can 
gather, whether their life in Fly-state is reckoned by 
hours or may include the active time at the beginning 
and end of the hybernation of the winter months in this 
Fly-state, they take no food. 
The Bot Flies are divided, according to their habits in 
the larval or maggot-state, into three main sections, 
namely, the Gastric, which feed within the stomach, of 
which the maggots of the Great Horse Bot Fly, CEstrus 
( Gastrophilus ) Equi, may be taken as an example; the 
Cutaneous, of which the maggots of the Ox Bot Fly, 
CEstrus ( Hyq)oclerma ) bovis, feeding within the tumour¬ 
like swelling on the back or sides of our cattle, is a well- 
known instance ; and thirdly, what are sometimes called 
