46 VETERINARY PARASITOLOGY 
thorax chestnut, with four black longitudinal stripes ; 
abdomen yellowish-white, composed of five segments 
(the last four each carry a large black spot) ; wings more 
opaque and more leaden in colour than those of the 
house-fly. It is this fly that conveys the dreaded 
nagana of Africa. 
3. The stride. 
These are exclusively parasitic. They have large 
wings, and the body is usually covered with downy hair. 
The abdomen is composed of six rings, and terminates 
in an extensile ovipositor. By means of this the female 
deposits eggs on some portion of the body. The larval 
stage is parasitic. 
Hypoderma Bovis.—Length, 13 to 15 millimetres. 
Head grey ; thorax grey on anterior half, black on pos- 
terior half, and bears wide longitudinal black bands ; 
abdomen black, shows three bands of coloured downy 
hair, anterior yellow, middle black, posterior orange ; 
wings brownish. 
The fly is active from the beginning of July to the 
beginning of September. It lays its eggs along the back, 
shoulders, and occasionally on the fore-limbs. The flight 
of this insect is accompanied by a loud buzzing noise, 
which terrifies cattle, although no pain is caused by the 
fly, as the ovipositor is soft, and does not penetrate the 
skin. The female deposits only one egg at a time, and 
then leaves the host, makes a short flight, and returns 
to repeat the process ten or twelve times. The eggs are 
white and elongated, and carry a brown terminal 
appendage, which fastens them to the hairs. 
The larvee are known as “ warbles,” and live in the 
subcutaneous tissue. Probably the eggs or young larvee 
are licked off, and after passing into the alimentary 
tract, finally reach this position. Nothing is noticeable 
during the winter, but in the following spring small non- 
