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Because we're fighting a total war,
our forces must be marshaled against every enemy,
unseen, as well as seen,
in every place, all of the time.
Millions of insects constitute an important part of our foes,
in their way, as militant as the Axis.
Their menace multiplies as they multiply.
Because in some areas more men were being incapacitated from action by insect-borne diseases than by battle casualties,
a search for a more powerful insecticide than had previously been known was imperative.
The answer to the quest for a poison to eradicate the insects
which threatened the morale, health, and military efficiency of our troops was found in DDT.
By intensive research, the nation's leading insecticide experts
have determined the forms of DDT best suited to the needs of the armed forces.
To this government laboratory, potential insecticides are submitted for evaluation.
When the first sample of DDT was submitted in November 1942, it underwent routine tests.
First synthesized by a German chemist in 1874, DDT had not been recognized as an insecticide until 1939,
when a Swiss chemical firm began to use it against moths and plant lice.
It arrived unheralded, but inherent was the power to curb epidemics.
For almost two years after its arrival in the United States,
DDT was available only in quantities sufficient for experimentation.
During this period, a formula for DDT emulsion concentrate, the golden liquid in the flask, was developed.
It was found that the ideal dilution is one part emulsion concentrate to four parts water.
This produces a 5 percent DDT emulsion.
When thoroughly mixed, the DDT hangs in suspension.
If this mixture is sprayed, the DDT makes a residual deposit.
It was also found that when the mixture stands for 24 to 48 hours, a creamy layer rises to the surface, indicating a breaking of the emulsion.
Yet, stirring returns it to its former constituency, and it regains its original effectiveness.
In comparing the relative effectiveness of DDT and fuel oils,
it was found that one half pint of 25 percent DDT emulsion concentrate is equivalent in insecticidal power to one gallon of two and one half percent DDT solution.
In either form, it is adequate to destroy mosquito larvae over an area of one acre.
Earlier larvaciding, without DDT, required 3 five-gallon jars of diesel oil per acre.
To repeat: one-half pint of DDT emulsion concentrate, or one gallon of two and one half percent DDT solution,
is equal in larvaciding power to 15 gallons of diesel oil.
Tests were also made to determine the physiologic effect of DDT upon insects.
Absorbed through the feet or other parts of the body,
DDT affects the nervous system and motor coordination of the insect.
Several hours elapse before symptoms develop.
Then, in sequence follow restlessness, tremors, convulsions, paralysis, and death.
Flies and mosquitoes react most quickly to this insecticide.
Death comes more slowly to bedbugs and roaches.
Complete annihilation of mosquito larvae requires 24 hours.
Under the influence of DDT, they become paralyzed, and are unable to return to the water's surface.
After a few hours, death ensues for all.
The sample in the center so closely resembles corn starch on the left, and flour on the right,
that obviously, this insecticide should not be stored in galleys.
Because oil solutions penetrate the skin, carelessness in handling them is dangerous.
If knapsack-type equipment must be used, it should be only half filled to avoid spillage.
Occasional contact is not harmful; repeated contact must be avoided.
One of the forms in which DDT is supplied in the Navy is the 100 percent powder for the preparation of oil solutions.
When exposed to atmosphere and sunlight, it does not evaporate nor deteriorate.
Unless all lumps are broken apart, a jelly-like coat, which defies solution, forms about them when they are mixed with oil.
Contact of the hands upon the dry powder is not dangerous,
for in this form, DDT is not absorbed through the skin.
The physical properties of DDT are such that it may be dispersed in emulsions, in oil solutions, or in dust solutions.
Oil solutions are probably the most useful form.
Diesel oil number two, as a solvent, gives excellent results, for it has a viscosity well-suited to the sprayers now in use.
The powder is thoroughly suspended in a small quantity of oil before it is added to the bulk in the drum.
Saturated fuel oils contain about nine percent DDT.
Crude kerosene dissolves about seven percent;
refined kerosene, less than four percent.
In mixing oil solutions, a special care against contact with the skin should be exercised, for the oil penetrates the skin.
Large doses of DDT lead to nerve and liver damage.
DDT goes into solution in oils rather slowly, requiring 12 to 24 hours.
The warmth of the sun, and hourly stirring by rolling, hasten the process.
DDT does not deteriorate under temperatures encountered in ordinary storage aboard ship or in the tropics.
When a dry mix is desired, the 10 percent DDT powder is diluted with fine road dust, condemned flour, lime, or soapstone.
One hundred percent DDT occurs in particles too large and hard to be broken up without heavy grinding equipment.
Hence, it cannot be diluted in the field for use as a dust.
Thorough mechanical mixing is required.
The strength of the mixture is determined by its intended use.
It would be difficult to scatter one pound of 10 percent dust evenly over one acre.
But 10 pounds of one percent dust may easily be spread over the same area.
Now let's consider the ways to disperse DDT.
Equipped with a supply of oil solution and power spraying equipment,
a malaria control squad enters an abandoned village, a reservoir of infection.
Within 24 hours, the vectors of typhus, yellow fever, malaria, dengue, filariasis, and dysentery begin to disappear.
DDT is not a repellent, however.
It kills...surely, but slowly.
Hence, its effectiveness cannot be measured by a count of dead insects,
for after receiving a lethal dose, the insects go elsewhere to die.
Residual treatment of the inner walls of these huts means that a contact poison awaits any insect which alights upon them for several weeks or months,
depending on variant factors, such as the intensity of the original treatment, rains, washing, prevailing winds, and so forth.
Using a paint sprayer, the worker spreads DDT evenly so that the entire surface is covered.
A semi-coarse spray is required for residual treatment.
A fine spray is lost in the air.
Experience teaches the correct amount to spray without waste.
The entire surface should be thoroughly wet, without runoff.
Residual treatment of all quarters pays big dividends in the health and happiness of the crew.
In a few hours, a two-man crew may treat hundreds of mattresses and bunks with five percent DDT and kerosene.
If correctly applied, this renders sleeping quarters free from bedbugs for many months.
Mattresses should not be slept on until the kerosene has evaporated,
and the smoking lamp should be out until the following morning.
Because DDT crystals cling tenaciously to the fibers of textiles,
cots, tents, and jungle hammocks should receive the residual treatment.
By treating bed frames and springs in this position, salvos are simultaneously fired against the bedbugs in the walls.
This increases efficiency, and eliminates waste.
Before treating galleys and mess halls,
food, trays, cooking utensils, and work tables must be covered.
Kerosene is used as a solvent for residual spraying of areas where stains from darker oils are to be avoided.
For residual treatment against roaches, 5 percent DDT in kerosene, fuel oil, or emulsion, is sprayed around pipes, in cracks, and in other places they frequent.
It is as effective as 10 percent DDT dust.
DDT crystals in the interstices of screens poison insects where they frequently alight.
Here, DDT emulsion is applied with paint brushes.
When the emulsion has dried, the screen has almost regained its former appearance.
An alternative method for treating screens is with an ordinary spray gun.
The insecticide is more apt to be wasted this way, however.
DDT oil solution leaves an effective residuum on garbage racks and other fly habitats.
Since these surfaces are frequently washed, repeated applications become necessary.
Because dysentery is second only to malaria as a threat to military operations,
it is especially important to treat the slit trench and surrounding areas.
Garbage pits, dugouts, and gun emplacements should be similarly sprayed.
Unless the entire bivouac area is treated, an influx of insects from adjacent areas may occur.
Bushes, logs, dead leaves, and the ground itself should be sprayed.
Residual treatment upon the inside of planes prevents the spread of disease vectors to uninfested islands.
This supplements, rather than replaces, the use of aerosol bombs in aircraft.
Either pressure- or hand-sprayers may be used.
For killing insects on the wing, a fine fog spray, wind drifted, has been found most effective.
Repeated fog applications may even leave a residuum.
Men with DDT aerosol bombs, walking briskly 20 feet apart, eradicate insects on the wing within the area traversed.
Excessive winds reduce the effectiveness of this treatment.
By the addition of DDT to Navy aerosol bombs, greater effectiveness against mosquitoes has been attained.
Flies, which previously defied this treatment, are now killed.
The effectiveness of DDT against lice was first proved in the field during the typhus epidemic at Naples.
The 10 percent powder is applied to the hair, and distributed between clothing and skin.
DDT dust is also useful in storerooms and the holds of ships.
Projected through a nozzle extension, it penetrates to the haunts of roaches.
It should be applied generously around cracks and crannies.
The rotary duster distributes DDT dust in areas frequented by flies, roaches, and ants.
Here it lies, until carried away by wind or rain.
Less tenacious than the residuum of the oil solution, it is nevertheless a persisting poison against insects.
If the worker stands to windward, it is not necessary to wear a mask when dispensing DDT dust.
For complete mosquito control, larvaciding is essential.
Solutions drifted by wind over water at the rate of one-tenth pound of DDT per acre destroy larvae within 24 hours.
These obvious breeding places are rendered harmless when minute quantities of DDT are ejected from a small hand sprayer.
The drip can method, wholly ineffective where there are strong currents, may be used for larvaciding still water or slow streams.
The figures sound fantastic, but one part of DDT in twenty million parts of water killed all larvae.
In the absence of other equipment, DDT solution may be poured onto the surface of ponds. However, this is not a preferred method.
Oil solutions of DDT remain on the surface. Emulsions penetrate the depths. Therefore, the latter requires heavier dosage.
Whatever the method or the solution, with proper dosage, most larvae die within 24 hours.
The greatest potentiality of DDT lies in dispersal from planes.
This assures even distribution, coverage of otherwise inaccessible areas, and conservation of manpower.
This is the only method whereby insect control may be established shortly after D-day.
Five percent DDT in equal parts of diesel and lubricating oil is spread at the rate of two quarts per acre.
Dispersal of DDT by planes combines features of three methods of treatment previously presented.
Descending through the air, it kills adult insects on the wing, as the fog treatment does.
Experiments and inventions are constantly being made to improve DDT formulae and methods of application.
The pocket atomizer, comparable in size to a fountain pen, may soon be supplied for individual use.
Work in progress indicates that DDT may also be sprayed from fast planes, or it may be dispersed explosively.
In this rapidly evolving field of insect control, new methods are constantly being sought and tested.
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