These are the conditions in nature. But the attempts to subject dragon-fly life to the rules of art do not appear to have been successful. Mr. Weeks tried earnestly and most intelligently to raise the insects artificially on his father's farm on Long Island and in his house in Brooklyn, and failed to obtain any results worth boasting about. He finds that they are diurnal, working in the sun, and never present at night, when the mosquitoes are busiest; that they are short-lived, and frequently destroyed in large numbers by heavy showers and winds; that, with few exceptions, they confine themselves to the vicinity of their place of birth, and, if removed therefrom, quickly return—hence, can not be colonized; and he concludes that "an attempt to destroy flies and mosquitoes by the artificial propagation of dragon-flies or any other insect would be unprofitable, unadvisable, and impracticable."
Mr. Beutenmuller thinks that positive statements can not yet be made respecting the expediency of artificially breeding dragon-flies for use against the mosquito. Differences in the habits of the two insects are against the scheme. Dragon-flies seek open places and the sun, while the mosquito finds hiding-places in the woods and in tall grass. "Under these circumstances the dragon-fly will not find its prey. Great numbers will escape; only those encountered in its busy flight through the air will be captured, for the dragon-fly does not hunt for its booty nor scour the forbidden shadows of woods and forests, and at nightfall the mosquito will elude his pursuer and rise to his murderous intent." But the dragon-fly "may, in some genial locations, suit the elements of the question and be of practical service; it may, indeed, be more widely beneficial than we suspect."
Of other means of keeping down mosquitoes, Mrs. Aaron recommends flushing the breeding-places with water, draining swamps, creating active artificial currents, encouraging fish, and spraying their hiding-places with petroleum. Mr. Weeks has faith in the enforcement and observance of sanitary laws and the encouragement of birds. Mr. Beutenmuller advises the use of lanterns so arranged as to attract and destroy the mosquitoes, with pans of kerosene or other strong mixtures for their destruction, which may be placed around houses and hotels and in marshes, general and scientific drainage of swamps; encouragement of fish and waterfowl; and, where the conditions are favorable, the use of coal-oil in the waters of estuaries of rivers and on the rain-invaded areas of deep woods for destruction in the larval stages. Astringents, like logwood or alum, will also prevent the growth of the mosquito in its incipient stages. Dr. H. C. McCook thinks it might be well to call spiders into service.
