3030 THE JOINTED ANIMALS 



stables in the vicinity. By means of its proboscis this fly pierces the skin of cattle 

 and horses, or even of man, and gorges itself on the blood. Its eggs are laid in the 

 excrement of the cattle on which it feeds. Resembling Stomoxys in habits and in 

 the structure of its antennae and mouth parts, the tsetse fly ( Glossina morsitans) of 

 Equatorial Africa, although barely equaling a blowfly in size, is one of the greatest 

 pests to domestic cattle, as the following accounts amply testify. As shown in the 

 annexed illustration, the proboscis of this fly is long and prominent, and the antennas 

 (b) are peculiar in that the third segment is very long and produced almost as far 

 as the apex of the flagellum, which is furnished with barbed hair along its outer 

 surface only. Writing of the tsetse, Livingstone says that "we had come through 

 another tsetse district by night, and at once passed our cattle over to the northern 

 bank, which, though only fifty yards distant, was entirely free from the pests. 

 This was the more singular that we often saw natives carrying over raw meat with 

 many tsetse upon it. This insect is not much larger than the common house fly, 

 and is nearly of the same brown color as the honeybee. The after part of the body 



TSETSE FLY (enlarged). 

 a. Side view of head ; b. Antenna. 



has three or four yellow bars across it. It is remarkably alert, and evades dexter- 

 ously all attempts to capture it with the hand at common temperatures. In the 

 cool of the mornings and evenings it is less agile. Its peculiar buzz when once 

 heard can never be forgotten by the travelers whose means of locomotion are domes- 

 tic animals, for its bite is death to the ox, horse, and dog. In this journey, though 

 we watched the animals carefully, and believe that not a score of flies were ever 

 upon them, they destroyed forty-three fine oxen. A most remarkable feature is the 

 perfect harmlessness of the bite to man and wild animals, and even calves so long 

 as they continue to suck the cows, though it is no protection to the dog to feed him 

 on milk. The poison does not seem to be injected by a sting, or by ova placed 

 beneath the skin, for, when the insect is allowed to feed freely on the hand, it 

 inserts the middle prong of the three portions into which the proboscis divides some- 

 what deeply into the true skin. It then draws the prong out a little way, and it 

 assumes a crimson color as the mandibles come into brisk operation. The previously 

 shrunken belly swells out, and, if left undisturbed, the fly quietly departs when it 

 is full. A slight itching irritation follows the bite. In the ox the immediate effects 



