820 
Annual Report for 1893 of the Zoologist. 
mixture likely to prove objectionable to the fly. Soot and water, cow- 
dung and earth, oil, and other substances have been used for this 
purpose. When a crop shows signs of failure from this cause, and espe- 
cially if there be any prospect of rain, a nitrate of soda dressing will 
often have a highly beneficial effect. 
Mangel-Leaf Maggot. 
Larva of Anthomyia beta:, Curtis. 
This pest, which strongly resembles the foregoing, except in its 
habit of attacking leaves and not roots, was reported from Renfrew- 
shire at the end of May. Mr. Alexander Cross has since written with 
regard to it : “I dressed the mangel with nitrate of soda, and they 
were fortunate in receiving rain at the proper time, and immediately 
afterwards they threw off the disease and have grown into an excellent 
crop.” 
Sheep Bot-fly. 
GEstrus ovis, Linn. 
In April complaints were received with regard to this pest from 
Somersetshire, where it was the cause of the loss of numerous sheep. 
Life-history. — The moderate-sized grey fly is found throughout 
the summer. It shelters at night and on dull days in the crannies 
of walls. In hot weather the female seeks the sheep and endeavours 
to deposit its eggs, or perhaps its already-hatched larva?, upon the 
nostrils. As if aware of its intention, the sheep manifest great 
uneasiness, and rub their noses in the dust, often so violently as 
to cause abrasion. The fly usually succeeds in its attempt w’hile 
its victims are nominating. The larvae pass into the nasal cavities, 
whence they sometimes migrate into the sinuses of the forehead or 
jaws, where they remain, living upon the products of the irritation 
they set up, for about ten months. 
The larva is then fully grown, and, loosing its hold, it causes the 
sheep to snort violently and eject it from the nostrils. It immediately 
pupates, and the mature fly emerges in five or six weeks. 
Symptoms. — Sheep are often slightly infested without showing 
signs of experiencing any great inconvenience ; when more severely 
attacked, they frequently throw up and shake the head. There is a 
running at the nose, accompanied by vigorous snorting. Badly 
infested sheep appear to walk with difficulty, and are often attacked 
with giddiness. They do not turn round, however, as in the case of 
“ gid ” caused by “ bladder- worm ” (the cystic phase of the tape-worm 
( Ccenurus cerebralis), which is an entirely different pest. Their 
appetite fails ; they lose flesh, and frequently die in convulsions. 
Prevention. — Larvse found in the heads of dead sheep, or seen to 
escape from infested animals, should be carefully destroyed. Places 
where sheep are housed should be limewashed, and may be fumi- 
