OX WARBLE FLY. 
115 
NOTES on OX WABBLE FLY or BOT FLY 
(Hypoderma Bovis, De Geer.) 
2 13 
1, Ox Warble Fly ; 2, maggot; 3, chrysalis. 
The Ox Warble Fly, or Bot Fly, is a two-winged fly, upwards 
of half an inch in length, so banded and marked with differently 
coloured hair as to be not unlike a Humble Bee. The face is yel¬ 
lowish ; the body between the wings yellowish before and black behind : 
and the abdomen whitish at the base, black in the middle, and orange 
at the tip. The head is large : the wings brown ; and the legs black or 
pitchy, with lighter feet. 
The female is furnished with a long egg-laying tube; but whether 
she inserts her eggs into the hide or lays them on it has not been 
made out with certainty. 
Egg-laying takes place during the summer ; it may begin in the 
month of May, but the time varies with the weather, and with the 
cattle being on low land or hill pastures, and other circumstances. The 
egg is oval and white, with a small brownish lump at one end. 
When full grown the Warble-maggot is the shape figured above. 
The mischief may first be found on the flesh side of the hide early 
in the winter. Specimens received from Messrs. Hatton, Hereford, 
on November 13th, showed the first appearance as small swellings 
bluish in colour, as if half a large shot was under the skin, and much 
inflamed round. The maggots were very minute and blood colour, 
and lying free (not in a cell) with a fine channel down through the hide 
to where they lay. 
The open Warble was first found towards the end of January, and 
by the end of February open Warbles were noticeable in many places, 
and the maggot was now white (not being feeding in bloody matter), 
worm-like, and with strong mouth-forks ; in its next stage it was club- 
shaped, and had a power of inflating itself by drawing in fluid until 
it was almost as hard and transparent 
as ice, and, lying small end uppermost, 
thus kept pressing the opening through 
the hide larger. In its next stage it 
gained its well-known shape, with a 
thicker and more prickly skin, the Warble 
cell at the same time gaining its mem¬ 
branous coating. 
The maggot can move up and down, 
but commonly has its brownish-tipped 
tail at the opening, and it draws in air 
i 2 
Maggots. 
Club-shapecl. Worm-like. 
Magnified. 
