. Preventive medicine and hygiene. mosquitoes convey the infection, the preventivemeasures must be along general lines; a combination of those describedunder malaria and yellow fever, as well as general sanitation and per-sonal hygiene. FLIES The true flies have but two wings, that is, they belong to the orderDiptera. They comprise an enormous number of species. Contrary topopular opinion, flies are poor scavengers. Most flies prefer the sun-shine, but species vary greatlyin their habits and breedingplaces. However, surprisinglylittle is known of the life his-tory and habits of most
. Preventive medicine and hygiene. mosquitoes convey the infection, the preventivemeasures must be along general lines; a combination of those describedunder malaria and yellow fever, as well as general sanitation and per-sonal hygiene. FLIES The true flies have but two wings, that is, they belong to the orderDiptera. They comprise an enormous number of species. Contrary topopular opinion, flies are poor scavengers. Most flies prefer the sun-shine, but species vary greatlyin their habits and breedingplaces. However, surprisinglylittle is known of the life his-tory and habits of most subject lacks attraction—especially the maggots or larvalstage. The life history of theliouse fly in general was, downto 1873, mentioned in onlythree European works, and fewexact facts were given. Dr. Packard, then of Salem, Mass., studied the house fly and gave descriptions of all its stages,showing that the growth of a generation from the egg to the adultoccupies from 10 to 1-1 days. In 1895 Howard further traced the life. Fig. 27.—House Fly {Musca domestica).Showing Proboscis in the Act ofEating Sugar. 248 INSECT-BOENE DISEASES history and indicated that 120 eggs are laid by a single female, andthat a generation is produced every 10 days at the summer tempera-tures of Washington. There may be, therefore, 12 generations in asummer. If each female lays only 120 eggs (1,000 have been noted),we have the possibility of countless millions coming from a single fly during a single sea-son. Allowing 2,880 fliesto the ounce, it has beenestimated that the totalproduct of a single fly in40 days would equal 810pounds, provided onlyone-half of them sur-vived; hence, the logicaltime to begin fly sup-pression is in the earlyspring. Flies transmit disease in one of several ways. The biting flies,such as the tsetse flies, which transmit sleeping sickness, inoculate thetrypanosome directly into the system by piercing the skin with theirmouth parts. The common house fly does not bite.
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
