. A manual of veterinary hygiene. Veterinary hygiene. 428 VETEEINAEY HYGIENE. the larvffi are found to occupy, the Cuticola, Gastricola and Caricola, of which the Ox Warble, Horse Bot and Sheep Nostril flies are examples. The object with which all bot flies attack animals is to deposit their eggs or larviE only. The adults have their mouth parts prac- tically abortive. Hypoderma bovis, Ox ivarhle or Bot Fly (Fig. 180), is one of the most severe insect pests to cattle living in the open. â r -v The fly by its presence is said to alarm Fig. gattle, and causes them to gallop wildly
. A manual of veterinary hygiene. Veterinary hygiene. 428 VETEEINAEY HYGIENE. the larvffi are found to occupy, the Cuticola, Gastricola and Caricola, of which the Ox Warble, Horse Bot and Sheep Nostril flies are examples. The object with which all bot flies attack animals is to deposit their eggs or larviE only. The adults have their mouth parts prac- tically abortive. Hypoderma bovis, Ox ivarhle or Bot Fly (Fig. 180), is one of the most severe insect pests to cattle living in the open. â r -v The fly by its presence is said to alarm Fig. gattle, and causes them to gallop wildly oovis; natural size. ' , , about, so much so that cows may even bruise their udders in their panic. The flight of the fly is rapid, it hovers over the cattle, then suddenly drops and deposits an egg on the back, rises again and repeats the manoeuvre. The egg is now fixed to the hair, and hatches in the open into a maggot, which then proceeds to make a hole for itself in the skin. It lies beneath the skin during the autumn and winter, during which time it moults, grows, and changes its appearance and colour. In the spring a tumour forms, which has an opening in the centre, leading down to the ' warble cell.' Through this opening the maggot when full grown (Fig. 181) squeezes its way, and falls to the ground, where it be- comes a pupa and finally the fly emerges. It has now been shown, in the case of H. lineata, the common American species of Warble fly, that the embryo is licked off the skin, and being taken into the mouth it fixes to the throat and then bores its way to below the skin of the back where the Warble is formed. It is possible that this will also be proved for H. bovis. The fly is about i inch long, with yellow hairs on the face, yellow and black hairs on the thorax, while those on the abdomen are yellowish white in front, black in the middle, and yellowish-red posteriorly. The maggots do considerable damage to animals from the irritation set up in them, while the
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