THE MOSQUITO Dangers from Mosquitoes. — A world-wide campaign is being carried on to exterminate the mosquito pest. The reason of this is found in the re cent discovery, that mosquitoes are the sole means whereby malaria and yel low fever are communicated to man, and the suspicion that they com municate other diseases. The fact that mosquitoes and malaria seem to go together has long been noted, and like wise the fact that malaria seems to be contracted after nightfall, but un til recently the part played by mosqui toes in communicating malaria was not understood. The notion that the mists arising from swamps and stagnant water at nightfall convey the germs of malaria to man is now quite ex ploded. In 1880 Lavaren, a surgeon in the French army at Algiers, first identified the parasites of malaria in human blood. In 1898 two English men, Manson and Ross, showed posi tively that malaria is transmitted by mosquitoes. In 1900 two English physicians, Sambon and Lowe, occu pied a house in one of the most mala rial districts in the world, the well known Campagna in Rome. The house was screened against mosquitoes. The two men were quite free from malaria and chills, while people living near by in houses not screened were fever-rid den. Mosquitoes which had bitten malarial patients were sent to Eng land and allowed to bite persons who had never had malaria or been ex posed to it, but who thereupon devel oped typical cases of the disease.
Similar experiments made by a med ical commission of the United States Army near Quamados, Cuba, prove that the mosquito also transmits yel low fever. The commission erected a small wooden building tightly sealed and screened against mosquitoes. For 63 days seven noncommune men occu pied this building. They used un washed bedding from the beds of genuine yellow-fever patients without contracting yellow fever.
In another experiment .L house was built having two rooms separated by wire screens. The house was tightly screened against mosquitoes. Its en tire contents were disinfected, and both rooms were occupied by persons not immune to yellow fever. Mosqui
toes which had bitten yellow-fever pa tients were placed in one room, but not in the other. In the room con taining no mosquitoes none had yel low fever, but in the other room six out of the seven that were bitten by mosquitoes developed genuine cases of the disease. These experiments led to scientific observations which have proved that a certain species of mos quito—the Anopheles—is present in all malarial and yellow-fever districts, but apparently not elsewhere; and also that the germs of malaria required for their development during a part of their life history occur as parasites in the bodies of the Anopheles mos quito.
These facts are stated at length to remove all doubts about the connec tion between malaria and yellow fever and the mosquito, and to impress the fact that such diseases are prevent able. If they occur in any locality, the responsible heads of families can not have a clear conscience until they have sought and removed the cause— namely, all near-by ponds or puddles of stagnant water in which mosquitoes breed.
Life History of Mosquitoes.—Tbe mosquito passes through four distinct stages: egg, larva, pupa, and adult. The female deposits her eggs, from 75 to 300 in number, toward the lat ter part of the night or early morning on the surface of stagnant pools. She rarely deposits them on running water or pure water that is frequently stirred. The egg hatches in about twenty-four hours or more, according to temperature. It produces the larva or well-known wiggler or wiggletail which everyone, may see in rain barrels or pools of stagnant water. The young larva rests just beneath the surface of the water, but breathes the outer air through a respiratory tube located at the tip of the abdomen. The larvae cannot live more than a minute or two if unable to reach the surface to breathe, and to this fact is due the common method of destroying them by means of a film of petroleum on the surface of the water.