HEALTH

NEW HAVEN DEPARTMENT OF HEALTH

Vol. XLIII, No. 5	May, 1918

This article excerpted from p. 3 of the issue.

To the average person mosquitoes are just mosquitoes, and are all alike, but if one examines them closely and studies their habits, marked differences will be found. For instance, certain kinds breed only in woodland pools, certain species on the salt marsh, certain kinds in fresh water swamps, and still other kinds in springs, in rain water barrels, tin cans, etc., and one species breeds in the cup-like leaf of the pitcher plant. In one respect they are all alike; i.e., their immature stages are passed in water. Water, then, is necessary for their existence. More than this it must be stagnant water, for they will not breed in swiftly-flowing water, nor in water containing an abundance of fishes, water beetles and water bugs, as these animals quickly devour the larvae or "wrigglers," as immature mosquitoes are called.

About 25 different species of mosquitoes have been recognized from Connecticut, and twice as many from the State of New York. Two of our species are known to transmit malaria through their bites; two kinds emerge in swarms from the pools of the unditched salt marsh; and one kind breeds in pools, tin cans, and all kinds of receptacles filled with rain water.

It is only the female mosquito which sings and bites; the male can do neither and only indirectly affects humans. In our opinion he doesn't amount to much. Probably Kipling had the mosquito in mind when he wrote his poem, for surely in the mosquito world "the female is more deadly than the male."

Most kinds of mosquitoes fly only a short distance from their breeding places, but the salt marsh species are an exception and are known to migrate inland some thirty miles in search of food, which consists of the blood of man or one of the higher animals, and this is apparently essential to the development of the eggs. Of course, most salt marsh mosquitoes,in Connecticut at least, can obtain from the summer inhabitants of the shore resorts plenty of the necessary food and there is no reason for migrating far inland.

The slogan used in New Haven a few years ago: "No stagnant water, no mosquitoes; no mosquitoes, no malaria," is true today not only for New Haven but for every locality.

The mosquito breeding season is now at hand. Let us take an account of stock so that we may know what to expect during the summer of 1918.

THE SALT MARSH MOSQUITO PROBLEM.

On a salt marsh mosquitoes breed in the shallow pools which fill with the unusually high or perigee tides. If water stands there for a week in warm weather, a brood of mosquitoes may develop and take wing from such pools. The deeper pools contain fish and the ditches are connected with tide water, the ebb and flow of which prevent breeding. Then, too, fish have access to every part of the ditch water. The proper treatment, therefore, is to cut deep and narrow parallel ditches sufficiently close together to take care of all the water when the high tides subside. Usually these ditches are about 150 feet apart, and ten inches wide and 24 inches deep, connected at one end with the main outlet and nearly perpendicular to it. Such ditching, properly done, and perfected and maintained at a small cost each year, will eliminate all mosquito breeding from a salt marsh. Special tools are made for the purpose and there are now several contractors who make this work their chief business.

Last year the city of New Haven appropriated $10,000.00 for mosquito extermination work, and after looking over the field, a committee appointed for the purpose reported in favor of ditching all remaining salt marsh area within the town limits much of such area having previously been ditched. Consequently the following ditching work was accomplished in 1917:

Mill River marsh is small and has never been a serious breeding place. It was not ditched because the Park Commissioners are now building a dam to flood a portion of this marsh; the remaining portion will be ditched if needed. Some new ditches may be needed this year in the rear of Morris Cove where the marsh was ditched in 1912, but on account of a defective tide gate and a silted channel in the outlet, the results were not wholly satisfactory. A new tide gate has since been constructed, and last summer Morris Creek was dredged so that the outlet will now take off the water, especially if the old ditches are cleaned and some new ones are cut. In East Haven the salt marsh has now been ditched as far cast as Momauguin. West Haven has a few small salt marshes which were ditched last year. There remains a small area on the west side of the river between Congress. and Derby Avenues, partly fresh in character, which should soon be given attention, but it is not a serious breeding place. The greater portion of the Quinnipiac marsh lies in the town of North Haven. Some of this area does not breed mosquitoes and a large part has been acquired by the railroad company and filled for freight and classification yards. Undoubtedly, at times portions of the city of New Haven will be invaded temporarily by mosquitoes front this marsh. Salt marsh mosquitoes bite in the daytime and have white rings on their legs. But as all salt marsh areas within the town of New Haven, and also adjoining in East Haven and Orange, have now been ditched, New Haven should be freer from the pest in 1918 than ever before.

THE RAIN-BARREL MOSQUITO NUISANCE.

Even though all large salt marshes and fresh water swamps are drained we may suffer from the bites of the house or rain barrel mosquito which enters houses and bites after dusk. This kind of mosquito breeds in rain water pools, rain barrels, tubs, buckets, tin cans, etc.: in fact in any receptacle which may fill with water when the first hard shower comes. Wherever any building operations are being carried on, there are usually tubs or barrels of water, and many householders carelessly leave around the premises tubs, kettles, or tin cans which serve as breeding places; then, too, old cisterns, clogged roof gutters, eave spouts and leaders occasionally furnish a breeding place and should be given attention. A little kerosene applied to the surface will kill all "wrigglers". Everyone should see that no such possible breeding places exist on his premises, but we cannot depend upon everybody to look out for this. Hence it is essential that municipal inspectors be sent from house to house for this purpose, and the health department of New Haven has for several years employed inspectors to look after such places, more particularly around the stables and dumps.

If mosquitoes are troublesome just after dark, it is reasonable to suppose that they are rain-barrel mosquitoes and that their breeding place is close at hand, probably on the premises. The first thing to do then is to search for stagnant water, for without stagnant water there can be no mosquitoes. Of course, the weather has much to do with the presence or absence of mosquitoes. If

rains are abundant, all receptacles and depressions will fill with water and some of them breed mosquitoes, but if there are no receptacles and no depressions to hold water, there will be no mosquitoes even in a wet season.

Occasionally a dry season aggravates the scourge of rain barrel mosquitoes, particularly in polluted streams. Heavy rains would flush the channel and clean out the "wrigglers". At three different times the house or rain barrel mosquito has been found breeding (and once very abundantly) in the upper part of West River where the water is polluted by the waste from the factories. This pollution either killed or drove away the fish which under ordinary circumstances would devour the wrigglers. The breeding was most intense during a protracted drought and in order not to waste the water that would be required to flush the stream, the River was oiled at an expense of about $150.00. This treatment instantly killed the "wrigglers", and as rains soon came there was no further trouble that season. The River must be watched, however, each season until the proposed sewer has been installed, and the water rendered fit to support the fish life, and if serious mosquito breeding occurs there, the stream must be flushed or oiled.

THE SCOURGE OF MALARIA MOSQUITOES.

The two kinds of mosquitoes which transmit malaria usually breed in fresh, clear water, particularly in the grassy margins of springs and slow-running streams. The "wrigglers" are never as abundant as the other kinds mentioned and the adults do not emerge in swarms. They fly only short distances, bite after dark, and occasionally enter dwelling houses. The "wrigglers" have short breathing tubes and lie flat at the surface of the water when breathing; the other kinds have long breathing tubes and hold their heads downward.

From the observations gathered through a period of fourteen years, it seems certain that Beaver swamp is the most prolific source of malarial mosquitoes around New Haven. As the land is now owned or controlled by the City through its Park Commissioners and plans for its improvement are now being considered, it is only a question of time (and I hope a short time) before this menace to public health will be removed.

Undoubtedlv malarial mosquitoes breed in many other regions about the city, but in small numbers when compared with Beaver swamp. Eternal vigilance is the price of freedom from malaria and from mosqitoes.

A WORD ABOUT FLIES.

Though the major portion of this discourse concerns mosquitoes, I wish to speak of the fly nuisance, which like the mosquito plague, is not only a serious annoyance but also a menace to health. That flies by their habits of breeding in filth and visiting filth, and then crawling over human food, have been responsible for many epidemics of typhoid, cholera and other enteric diseases, has been proven many times during the past twenty years.

Though the chief breeding place for the common house fly is in horse manure, it will breed, to a limited extent, in compost heaps, garbage cans, refuse on the dumps, and particularly in the dry earth closet or privy; the sooner the privies of New Haven are abolished and water closets installed, the better will be the health record of the city. Special attention should be given to the wastes from military and construction camps. Horse manure may now be handled so that it will not supply the community with swarms of flies. It may be removed daily or at least weekly and spread upon the land. If allowed to accumulate, the manure should be kept in a dark screened pit or treated with chemicals. Commercial borax sifted on the fresh manure each day at the rate of one pound to each twelve bushels of manure, or fresh hellebore (one-half pound in ten gallons water) sprinkled upon eight bushels of manure, will prevent fly-breeding therein. The cost is about one and one-half cents per horse per day or one-half cent per bushel of manure.

But in the anti-fly work as well as in the anti-mosquito work, close inspection is necessary, because many persons do not realize the importance of such matters; others become careless and fail to do their best; hence much publicity and a strict enforcement of health regulations are necessary before we can hope to see the millennium.