. A civic biology : presented in problems. Biology; Sanitation. 222 THE ECONOMIC IMPORTANCE OF ANIMALS Another fly carries a species of trypanosome to the natives of Central Africa, which causes " the dreaded and incurable sleep- ing ; This disease carries off more than fifty thousand natives yearly, and many Europeans have succumbed to it. Its ravages are now largely confined to an area near the large Central African lakes and the Upper Nile, for the fly which carries the disease lives near water, seldom going more than 150 feet from the banks of streams or lakes. The Briti
. A civic biology : presented in problems. Biology; Sanitation. 222 THE ECONOMIC IMPORTANCE OF ANIMALS Another fly carries a species of trypanosome to the natives of Central Africa, which causes " the dreaded and incurable sleep- ing ; This disease carries off more than fifty thousand natives yearly, and many Europeans have succumbed to it. Its ravages are now largely confined to an area near the large Central African lakes and the Upper Nile, for the fly which carries the disease lives near water, seldom going more than 150 feet from the banks of streams or lakes. The British government is now trying to control the disease in Uganda by moving all the villages at least two miles from the lakes and rivers. Among other diseases that may be due to protozoans is kala-agar, a fever in hot Asiatic countries which is probably carried by the bedbug, and African tick fever, probably carried by a small insect called the tick. Bubonic plague, one of the most dreaded of all infectious diseases, is carried to man by fleas from rats. In this country many fatal diseases of cattle, as " tick," or Texas cattle fever, are probably caused by protozoans. The Fly a Disease Carrier. - - We have already seen that mos- quitoes of different species carry malaria and yellow fever. An- other rather recent addition to the black list is the house fly or typhoid fly. We shall see later with what reason this name is given. The development of the typhoid fly is extremely rapid. A female may lay from one hundred to two hundred eggs. These are usually deposited in filth or manure. Dung heaps. Life history of house flies, showing from left to right the eggs, larvae, pupae, and adult flies. (Photograph, about natural size, by Overtoil.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hunter, George W.
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