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Household and Garden Pests: Mosquitoes

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 recent discovery that mosquitoes are the sole means whereby malaria and yellow fever are communicated to man, and the suspicion that they communicate other diseases. The fact that mosquitoes and malaria seem to go together has long been noted, and likewise the fact that malaria seems to be contracted after nightfall, but until recently the part played by mosquitoes 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 exploded. In 1880 Lavaren, a surgeon in the French army at Algiers, first identified the parasites of malaria in human blood. In 1898 two Englishmen, Manson and Ross, showed positively that malaria is transmitted by mosquitoes. In 1900 two English physicians, Sambon and Lowe, occupied a house in one of the most malarial districts in the world, the wellknown 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-ridden. Mosquitoes which had bitten mararial patients were sent to England and allowed to bite persons who had never had malaria or been exposed to it, but who thereupon developed typical cases of the disease. Similar experiments made by a medical commission of the United States Army near Quamados, Cuba, prove that the mosquito also transmits yellow fever. The commission erected a small wooden building tightly sealed and screened against mosquitoes. For 63 days seven noncommune men occupied this building. They used unwashed bedding from the beds of genuine yellow-fever patients without contracting yellow fever.

In another experiment a house was built having two rooms separated by wire screens. The house was tightly screened against mosquitoes. Its entire contents were disinfected, and both rooms were occupied by persons not immune to yellow fever. Mosquitoes which had bitten yellow-fever patients were placed in one room, but not in the other. In the room containing no mosquitoes none had yellow 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 mosquito-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 mosquito.

These facts are stated at length to remove all doubts about the connection between malaria and yellow fever and the mosquito, and to impress the fact that such diseases are preventable. If they occur in any locality. HOUSEHOLD AND GARDEN PESTS the responsible heads of families cannot have a clear conscience until they have sought and removed the causenamely, all near-by ponds or puddles of stagnant water in which mosquitoes breed.

Life History of Mosquitoes. - The mosquito passes through four distinct stages: egg, larva, pupa, and adult.

The female deposits her eggs, from 75 to 300 in number, toward the latter 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 larvæ 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.

In five or six days the larvæ change into pupæ. In about two days more these assume the form of the ordinary adult mosquito. Hence in hot weather a generation of mosquitoes develops in from eight to ten days. Considering the number of eggs laid by a single female it will be readily seen that countless millions of these pests may breed in a single pool, pond, or swamp during one summer season.

To Destroy Mosquitoes. - Happily, the experiments of scientific observers seem to indicate that mosquitoes do not usually fly very far from the pools in which they were hatched. They require as breeding places pools of stagnant water that remain undisturbed for from ten days to two weeks, and they may be completely destroyed by covering the surface of these pools with a thin film of petroleum or kerosene oil. Hence the problem of exterminating mosquitoes is strictly a local one, and the means are quite within the reach of every responsible person. Farmhouses are often far apart, so that all the mosquitoes about the house and farm buildings are bred on the place. Consequently, the responsibility for exterminating them is purely an individual one.

Or a group of neighboring farmers can often be persuaded to act in harmony, or at least to permit an enterprising neighbor to take measures to prevent the breeding of mosquitoes in their vicinity.

School children may be encouraged to undertake the extermination of mosquitoes in an entire school district, or boards of health may be persuaded to take up the problem and appoint voluntary or paid representatives to wage a war of extermination through the entire community.

Kerosene for Mosquitoes. To destroy mosquitoes, apply petroleum or kerosene oil to the surface of the pools, puddles, or marshes in which they breed. One ounce of kerosene is sufficient for 15 square feet of stagnant water. Thus a tank or pool 10 feet across would require about 14 pints of the oil.

To apply the oil on small puddles, tanks, or pools, it is only necessary to pour it on the surface or scatter it to windward with a wide sweep of the arm.

The oil will spread itself over the surface in a uniform film. But for larger ponds, marshes, and pools overgrown about the edges with grass or weeds which may prevent the oil from penetrating to every part, it is better to use an ordinary sprayer having a fine nozzle, such as is used for spraying fruit trees with Bordeaux mixture. This may be applied in pools by wading or from a raft or boat.

A single application of oil kills all eggs laid upon the surface and all wigglers previously hatched. The film of oil prevents their coming to the surface to breathe, hence they are suffocated or "drowned." The oil does not prevent the female mosquito from attempting to deposit her eggs on the surface, but destroys her in the act of doing so, consequently, until the oil evaporates, the breeding of mosquitoes is totally prevented. The film of oil, if undisturbed, will not evaporate for a week or more, and at least ten days will be required after it has evaporated for a generation of mosquitoes to mature. Hence in absolutely still water where there is no current to carry off the oil, two applications a month will be quite sufficient. In covered tanks, drains, and cesspools not exposed to the sun, one application a month should be enough. But those who are fighting mosquitoes must remember that after a rain an old tin can, the print of a cow's foot in the mud, or a puddle left in a wagon rut or hollow may breed enormous numbers of mosquitoes if it remains undisturbed for a period of ten days or more. Hence a few days after a rain the ubiquitous small boy should be sent abroad with a small waterpot having a fine nozzle and containing a gallon or more of kerosene, and he should be instructed to cover the surface of these pools with a layer of the oil. Tin cans before being thrown on the dump should have the bottoms knocked out or a few holes punched in them with a can opener. An ounce of prevention is better than a pound of cure.

To Destroy Mosquitoes by Drainage. This needs little comment. Obviously, if swamps, pools, and the like have tile or other drains laid beneath their surface so that the water is entirely drawn off, mosquitoes cannot breed in them. But open drains are themselves favorite breeding places of mosquitoes. Hence these should be spread with oil, especially along the edges where grass and weeds make the current sluggish. If there is much current, they should be sprayed two or three times a month.

Rain barrels, buckets, and all other receptacles about the premises in which water collects should be emptied at least once a week or, if possible, permanently. Draining is the most satisfactory way to fight mosquitoes, as it is much easier to get people's interest in the subject thoroughly aroused by one concerted effort than it is to try keeping it up by spasmodic efforts from month to month and from year to year.

Screens for Mosquitoes. - Cover with fine wire screens rain barrels, cisterns, and all receptacles for drinking water that cannot be treated with kerosene or emptied frequently, and go over them occasionally with a cloth moistened in kerosene, taking care not to let any oil drip into the water.

This will effectually prevent mosquitoes from squeezing through the screen to lay their eggs.

To Destroy Mosquitoes with Fish. -The small pools, marshes, swamps, and streams having shallow pools with stagnant edges which are used as watering places for stock, and hence cannot be covered with kerosene, should be stocked with small fish, as the top minnow and the sunfish (or "pumpkin seed"). Both these species feed on the wigglers and will quickly rid any infested waters of them. The pumpkin seed is preferable, as it is equipped with spine rays which protect it from the larger fish. But the top minnow is suitable for small pools and ponds where there are no pike or pickerel.

When depending upon fish to keep the watering places of stock clear from mosquitoes, be on the lookout against prints left by the hoofs of animals in the mud on margins of ponds, where, of course, the fish cannot approach. These must be treated occasionally with kerosene. - Household Remedies. - To screen all doors, windows, and other openings, including the entrance to the top of the chimney and to the cellar windows, against mosquitoes may be, in malarial and yellow-fever districts or during epidemics of contagious diseases, a matter of life and death, and is the best preventive at all times against the annoyance of the pests.

An open porch or piazza fitted with movable screens or hinged screens that can be opened during the daytime if desired, is a great convenience and HOUSEHOLD AND GARDEN PESTS luxury in mosquito-ridden districts.

If mosquitoes crawl through the screens, rub the latter just at twilight with a cloth moistened in kerosene, or, if preferred, one of the essential oils, as pennyroyal or other preventives. oven.

Or burn Persian insect powder or pyrethrum in sitting or sleeping-rooms during the evening, moistening the powder with a little water and shaping it by hand to a rough cone about the size and shape of a chocolate drop. Place these cones in a pan and thoroughly dry them in the When wanted, set fire to the top of one, which will smolder slowly and send up a thin column of pungent smoke, not harmful to man but stupefying to mosquitoes. Two or three of these cones burned during the evening will give much relief from mosquitoes in sitting rooms. The smoke does not, however, kill the insects, and is merely a palliative. Or, to kill mosquitoes found in the evening on ceilings of sitting rooms or bedrooms, nail to the end of a broom handle or other suitable stick a shallow tin cup, such as the top of a blacking box, and wet the inside with kerosene. When this cup is placed under the mosquito, he drops or flies against the oily surface and is killed.

The last two methods are recommended by the United States Department of Agriculture.

Or place a bit of camphor gum the size of a butternut on iron or tin and hold it over the flame of a lamp until it evaporates. Do not let it take fire.

The smoke which fills the room will stupefy the mosquitoes.

Or scatter oil of pennyroyal about the room.