INSBETS AND DISEASE It has generally been recommended that the manure itself should be kept in a dark vault or pit from which flies are shut out by screens, or in a tight covered box. The health officer of Asheville, N. C., where an unusually successful anti-fly campaign has been carried out, believes that screening of manure has been over-emphasized and that tightly floored boxes and thorough and complete cleaning up of these floors at frequent intervals are the main desiderata. He points out that most manure already contains fly maggots when placed in the bin and that an elaborately screened bin is hard to clean so thoroughly that development may not take place in the manure left behind.
- A method of storing manure which is specially applicable to military camps depends on the fact that flies cannot breed readily in this material when it is closely packed. A rectangular area of sround is staked off and the manure is built up into compact heaps, the sides being kept straight and beaten hard with shovels. The adjacent ground is also beaten hard and loose straw is placed in small windrows about a foot from the edge. The absence of air in the interior of the heap, with the high temperature and chemical products due to bacterial fermentation, makes the manure highly unfavorable for fly development, and any larve which succeed in developing in the surface layer will pass out and pupate in the ring of straw, which should be swept up every two or three days and burned. The United States Bureau of Entomology has devoted special attention to the problem of chemical treatment of manure for the purpose of poisoning the maggots which might otherwise be bred therein. Any one who is interested in the control of this insect pest should write to the Bureau of Entomology, Washington, D. C., and to the Department of Agriculture of his own State, for the latest recommendations in regard to this method of treatment, which is constantly being improved and made more economical and efficient. The following suggestions are taken from Farmers’ Bulletin 851 of the United States Department of Agriculture and represent the best procedures available in 1917.
For manure or other refuse not to be used as a fertilizer, powdered borax is the best chemical preventive of fly breeding; .62 pound per 8 bushels of manure, or about 1 pound per 16 cubic feet, will destroy 90 per cent. of the larve present. The borax should be applied in solution, or water should be sprinkled on after scattering dry borax evenly over the pile.
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AMERICAN MUSEUM GUIDE LEAFLETS Borax-treated manure in large amounts may injure crops; and, for manure which is to be used on the land, powdered hellebore may be recommended. A water extract is prepared by adding % pound of powder to every 10 gallons of water, stirring and allowing to stand for 24 hours. The stock mixture thus prepared is sprinkled over the manure at the rate of 10 gallons to every 8 bushels (10 cubic feet) of manure. MHellebore, while more expensive than borax, in no way injures the manure.
A third alternative has been suggested by the Department of Agriculture, which, while showing a still higher first cost, involves the use of substances which serve directly to increase the fertilization value. A mixture of % pound of calcium cyanamid plus % pound of acid phosphate to each bushel of manure killed 98 per cent. of the larve when scattered evenly over the surface and wetted with water, at the same time adding to the manure the valuable elements nitrogen and phosphorus.
“It is well to bear in mind that the house flies breed in many substances other than horse manure, for example, in pig manure, chicken manure, ensilage, moist bran, rotting potatoes, and in decaying matter on the public dumps of towns and cities, and it is necessary to sive attention to all such accumulations where active fermentation is taking place.”’ A highly ingenious method of preventing breeding of flies in manure is the maggot trap devised by Dr. E. C. Levy, Health Officer of Richmond, Va. Its use is described by Mr. Hutchinson of the United States Bureau of Entomology as follows:
“The maggots of the house fly, when they have finished breeding, show a distinct tendency to migrate and will crawl away from the manure, especially if it is moist, in search of a comparatively dry and safe place to pass the pupal or resting stage. Now, if the manure is placed on a slatted platform, and if the platform stands on the floor of a concrete basin containing ™% inch or more of water, the larve in migrating will drop into the water and be drowned. Each day the stable cleanings should be placed on the platform and compactly heaped and well moistened. For the purpose of keeping the manure wet, it is best to have a small cistern close to the platform and a pump so placed that the watering of the manure heap is easily accomplished. If the liquid manure from the stables is conducted by drains to the cistern, the valuable plant food which it contains will thus be added to the manure on the maggot trap. Experiments have 22
INSECTS AND DISEASE Fig. 12. TRAP FOR THE DESTRUCTION OF FLY LARVA (Maggot Trap) 23
AMERICAN MUSEUM GUIDE LEAFLETS shown that the maggot trap will destroy 99 per cent. of the maggots developing in manure. After the manure has been standing on the maggot trap for 10 days it will be practically free from magéots and may be used on fields or gardens or stored in heaps without likelihood of any further breeding taking place init. The advantages of the maggot trap are that it is cheap, requires little extra labor to operate and to dispose of the drowned maggots, and it does not lessen the value of the manure but rather tends to preserve it. As is the case with all other methods, the use of the maggot trap must be supplemented by careful attention to possible breeding places other than horse manure.”
2. Destruction of Adult Flies Simple and effective flytraps may be used to some advantage in decreasing the number of flies. Their use has been advocated not only because of their immediate results, but because of the chance that the flies may be caught before they lay their first batch of eggs, and that thus the possible number of future generations will be materially reduced. | Many types of flytraps are on the market, and asa rule the larger ones are the more effective. Anyone with a few tools, however, can construct flytraps for a small part of the price of the ready-made ones. A trap which is very effective in catching flies, and is easily made, durable, and cheap, may be constructed as follows: “The trap consists essentially of a screen cylinder with a frame made of barrel hoops, in the bottom of which is inserted a screen cone. The height of the cylinder is 24 inches, the diameter 18 inches, and the cone is 22 inches high and 18 inches in diameter at the base. Material necessary for this trap consists of four new or secondhand barrel hoops; one barrel head; four laths; 10 feet of strips 1 to 1% inches wide by ™% inch thick (portions of old boxes will suffice); 61 linear inches of 12- or 14-mesh galvanized screening 24 inches wide for the sides of the trap, and 41 inches of screening 26 inches wide for the cone and door; an ounce of carpet tacks, and two turn buttons, which may be made of wood.’ The cost of the material for this trap is not great, and in many cases the barrel hoops, barrel head, laths and strips can be obtained without expense.
“In constructing the trap, two of the hoops are bent in a circle (18 inches in diameter on the inside) and nailed together, the ends being trimmed to give a close fit. These form the bottom of the frame 24
INSECTS AND DISEASE (A), and the other two, prepared in a similar way,’ the top (B). The top (C) of the trap is made of an ordinary barrel head with the bevel edge sawed off sufficiently to cause the head to fit closely in the hoops and allow secure nailing. A square, 10 inches on the side, Fig. 13. A SIMPLE FLYTRAP (see text) is cut out of the center of the top to form a door. ‘The portions of the top (barrel head) are held together by inch strips (D) placed around the opening one-half inch from the edge to form a jamb for the door. The door consists of a narrow frame (E) covered with screen (F) well fitted to the trap and held in place (not hinged) by buttons (G). The top is then nailed in the upper hoops and the sides (H) formed by closely tacking screen wire on the outside of the hoops. Four laths (1) (or light strips) are nailed to the hoops on the outside of the trap to act as supports between the hoops, and the ends are allowed to project 1 inch at the bottom to form legs (J). 25
AMERICAN MUSEUM GUIDE LEAFLETS The cone (K) is cut from the screen and either sewed with fine wire or soldered where the edges meet at (L). The apex of the cone is then cut off to give an aperture (M) 1 inch in diameter. It is then inserted in the trap and closely tacked to the hoop around the base.”’ The effectiveness of the traps will depend on the selection of a good bait. For attracting house flies beer is probably the best. It loses much of its attractiveness after the first stages of fermentation are over, and for this reason it should be renewed every day or two. Milk is also a good bait. Over-ripe or fermenting bananas, crushed and placed in the bait pans, give good results. A combination of bananas and milk is more attractive than either used separately. A mixture of 3 parts water and 1 part cheap molasses is very attractive after it has been allowed to ferment for a day ortwo. A mixture of equal parts of brown sugar and cheese (or curd of sour milk), thoroughly moistened, give good results after it has been allowed to stand for three or four days. For catching blow flies and other meatinfesting flies, the best bait is the mucous membrane from the lining of the intestines of hogs. Ordinary fish or meat scraps may be used. Fly paper is sometimes helpful, particularly the long slender roll of sticky paper hung froma ceiling. Fora fly poison, Professor Phelps of the United States Public Health Service recommends either formaldehyde or sodium salicylate, three teaspoonfuls of the 40 per cent. commercial solution of formaldehyde, or the same amount of powdered sodium salicylate to a pint of water. Nearly fill a glass tumbler with the solution, place over this a piece of blotting paper cut to circular form and somewhat larger in diameter than the tumbler, and over this invert a saucer. Invert the whole device. The blotting paper will remain in the proper moist condition until the entire contents of the tumbler have been used and the strength of the formaldehyde solution will be maintained. A little sugar sprinkled upon the paper will increase the attractiveness of the poison for the flies. Either of these preparations may be safely used where there are young children, although the addition of the sugar is not recommended in such cases.
The killing of flies in the house by ‘“‘swatters’’ is also of some value, although where the insects are abundant the majority of them should be eliminated by the more efficient methods of trapping. Among natural enemies which help to destroy flies in either the larval or the adult state are hens, swallows, phoebes and other birds, and toads.
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INSECTS AND DISEASE 3. Protection of Human Discharges from Access of Flies The measures suggested above will greatly reduce the numbers of flies but, as a rule, will not do away with them entirely. It is, therefore, always essential to take precautions against the spread of specific human diseases by guarding intestinal discharges from the access of flies. Outside closets, where they cannot be replaced by a cesspool or sewer system, should always be carefully constructed so as to exclude insects, all openings for ventilation screened, and cracks in walls or openings below the floor level tightly closed. In the army, the construction of fly-proof latrines is a first essential of camp sanitation.
4. Exclusion of Flies from Houses and from Access to Food. Finally, flies should be excluded from dwellings by careful screening of doors and windows. Screens must be always in place and must fit tightly. In particular, the kitchen and the dining room should be protected in this way.
The covering of foods in stores and restaurants is one of the most important aspects of the campaign for clean and pure foods, and it is wise to avoid all such places where flies are abundant and food unprotected.
_ AMERICAN MUSEUM GUIDE LEAFLETS THE MOSQUITOES AND THEIR ALLIES The blood-sucking habit, and the modifications of mouth-parts necessary to such a habit, are to be found in several, not closely related, Sroups of the two-winged insects, Diptera. All blood-suckers are to be looked on with suspicion, because of the possibility that they may be the intermediate hosts of disease-parasites. Several such insects have already been mentioned; but another group of quite different creatures remains to be discussed.
If a moquito, crane fly, or some similar insect, be carefully examined, it will be seen that the antenne (“‘feelers’’) consist of not less than eight joints, rather similar one to another; the antennz are usually longer than the thorax (the middle part of the body, the part which bears the wings and legs); the anal cell (see Fig. 14) is rarely narrowed in the border of the wing and the discal cell is usually absent. These are distinguishing characteristics of the nematocerous Diptera or Orthorrhapha, that group of Diptera to which mosquitoes, punkies, black flies, and blood-sucking gnats in general belong. Sone ee a Ep ELE SS SS i oF SSeS aA ye S y WSs.
1 \ < RIS Fig. 14. STRUCTURAL CHARACTERS OF THE MOSQUITO a. Antenna 6. Thorax ¢. Costal vein of wing d. Anal cell e. Tibia Of the Nematocera, there are four families (Culicide, Psychodid, Simuliide, and Ceratopogonidz) which contain blood-sucking species. The adults of the first two of these, Culicide and Psychodide, unite in typically having the following characteristics: at least nine 28