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[Narrator:] A common sight in and around many towns

and cities has been the spraying of oilon watered areas while the control

of pests and disease-bearing mosquitoes,control by this means has been expensive

or large quantities of oil were requiredand large oiling crews were needed.

The use of a small amount of DDTin the oil promises to change drastically

many larviciding practices.

The application of 25 to 35 gallons of oilcan be reduced to 1 gallon.

One man more highly skilledthan the laborers previously used

can take the placeof a fair-sized spraying crew.

Properly applied, a DDT solution

will control malaria mosquito breedingas well as most pest mosquito breeding

and will have no appreciable effecton fish or wildlife.

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[Narrator:] A commercially prepared larvicideor larvicide concentrate may be used,

but the mixing of the spray solution

is a simple and easy operationthat may be done locally if desired.

The 55-gallon drum in which the keroseneor a fuel oil is received at the plant

makes an excellent containerin which to mix the solution.

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[Narrator:] 500 of a pound of DDT are requiredfor every gallon of oil.

2.75 pounds will be neededfor this drum of kerosene.

It may be weighed out,

but a quart measure of a field twiceis sufficiently accurate for field use.

A spreading agent such as Triton B-1956,or [?] is desirable

since it makes the larvicidesspread more easily over the water surface.

One quart of such a spreading agent

is sufficient for a 55-gallon drumof solution.

The DDT, the oil, and the spreading agentare the only materials used

but it is necessaryto dissolve the DDT completely.

First, tighten the bond,

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then roll the drumover and over several times.

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This agitation of the drumshould be repeated several times

during the next two daysand the drum should be left in the sun

between agitationssince heat helps the DDT to dissolve.

After two days,the DDT will be completely dissolved

and the solution will be ready for use.

If the larvicide is needed immediately,

the DDT may be dissolved rapidly

by employing more forceful meansof agitation.

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Almost any pressure sprayer may be usedfor DDT spraying,

but the two-gallon hand sprayerin the foreground

is probably the most convenient.

It is especially equippedwith an oil-resistant hose,

a pressure gauge,and a pressure release valve,

and it is light enoughto be carried easily.

Filling is easy.

Remove the pump being carefulto wipe the funnel.

Place the pump on something cleansince dirt in the sprayer

may clog the nozzle.

Fill the sprayer tank 2/3 full,leaving the top third of the tank clear

so that the necessary air pressuremay be built up in it.

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Replace the pump and build upthe pressure until it reaches 50 pounds.

Now when the trigger is pressed,the liquid is forced

through the holes wandand atomizing nozzle and emerges

as a finely divided spray.

The nozzle itselfis probably the most important part

of the sprayer.

Almost any atomizing nozzle may be usedbut whatever the type,

it must be kept clean at all times.

A representative atomizing nozzleconsists of several parts,

the body, the plate,

the atomizing chamber, the spacer ring,the screen, and the locking nut.

When liquid passes through the nozzle,it is broken up into fine droplets

which emerged from the small holein the plate as a cone-shaped spray.

Pressure may be released from the tankby opening the small relief valve

and allowing the compressed airto escape.

Failure to release this pressurebefore removing the pump body

may result in it being blown outwith great force.

The gasket is almost certainto be ruined

and personal injury may occur.

The gasket may be replaced

by unscrewing the barrel of the pumpfrom the head.

On the bottom of the pumpis a small air check valve

it is easily replaced when worn.

Keep the sprayer clean

and pay particular attentionto the nozzle.

Clean it frequentlywhen the sprayer is in use.

A little maintenance will keep itin good working order.

Field methods for applying DDTare simple.

Remember to take with youthe necessary equipment, soap,

rags, a pail,a few gallons of the larvicide solution,

and the sprayer.

The DDT solution is applied

by drifting it downwindunder the water surface.

Consequently, the direction and the speedof the wind is important.

Check it with a burst of spray.

For best results,there should be very little wind.

Experience will teach

the maximum wind speedat which spraying is practical.

Now the wind is blowingfrom right to left,

that means that spraying will starton the right-hand

or upwind side of the pond.

Move along the edge of the pondat right angles to the wind.

Hold the nozzle of the sprayer

at about chest heightand drip the spray downwind.

The spray can be dependent uponto be distributed effectively

at least 30 feet downwind.

Thus, as you move along,a swath of 30 feet will be larviciding.

Upon reaching the far end of the pond,

return on a new line 30 feet downwindfrom the first line and parallel to it.

This will larvicideanother 30-foot swath parallel to

and adjoining the first.

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In this way,the entire pond may be covered.

The pace should be slow,about the same as a slow wedding march

or a 75 beep per minute.

Pace is important since it controls

the amount of spraydeposited on the water surface.

If the pace is too slow,too much larvicide will be deposited.

If it is too fast,

too little spray will reachthe water surface.

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The distance between swathsis paced off at the end

of each line of spraying.

Be sure to come all the way upon the bank,

so that the edges of the pondwill be sprayed.

How about a pondthat is too deep to wade?

If it is not more than 100 feet wide,

it may be larvicidedby drifting the spray across it

from the upwind bank.

To make the spray drift effectivelythis far,

move the wand up and downas you move along.

By watching the spray as it drifts out,

you can judge the height of the wandneeded to drift it

to the proper distance.

Keep the pace the same.

Naturally,covering a greater than 30-foot swath

at the standard basewill under-treat the area.

To obtain the proper dosage,

cover the line of sprayingmore than once.

Thus, for a 60-foot pond,cover the line of spraying twice.

For a 90-foot pond, 3 times.

One more thing,

keep a check on the pressurein the sprayer.

When the pressure drops to 30 pounds,stop and pump back up to 50 pounds.

Now, let's apply these methods

to some of the types of pondsordinarily encountered.

Here's one that's shallow enough to wade.

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The wind is blowing from right to leftso that the line of spraying

will cover the pond in this manner.

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This is also a wading pond,it differs from the preceding one,

only end of the vegetation hereis much heavier.

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It is larvicided in the same manner.

DDT is particularly effectivefor this type of pond

since it will more readily penetrateheavy vegetation than would oil or dust.

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This pond is too deep to wade,

but since it is approximately 60 feet wide,

the spray can be drifted across it

by varying the height of the wand.

The wind is blowing from left to right

so the spraying will be donefrom the near bank,

and the line of sprayingwill be covered twice.

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Here's a pond too deep to wade

and too wide to permit sprayto be drifted across it effectively.

Although the first swath may be appliedfrom the shore,

a bolt will be necessaryfor the remainder of it.

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The wind is blowing directly away from usso the line of spraying will be like this.

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Be sure to carry a can of larvicidewith you in the boat,

so that if the sprayer runs dry,it won't be necessary to return to shore.

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With the boat, the pace is the same

and the turns at the end are madein a similar manner.

Most ditches may be sprayed directly.

When the banks are clear,as in this case,

spraying can be accomplished easily.

Here, the banks presentmore of an obstacle

and spraying can be done more easilyby wading.

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No matter what the method of spraying,

the only sure proof of effectivenessis the absence of larvae.

Check the sprayed ponds regularly.

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In this check, no larvae were found,an indication of effective larviciding.

With proper mixing, care of equipment,and the correct application,

DDT can be depended uponto effectively control naphthalene

and [?] mosquito breeding

with no appreciable effecton fish or wildlife.

Five-hundredths of a pound of DDT per acre

is the foundation blockon which the process rest.

Factors in the process are swathwidth, concentration of the larvicide,

speed of wind,the air pressure in the sprayer,

and the movement of the sprayer.

If all these factors in the process

are standardizedand carried out faithfully,

they will supporta standardized application,

which will controlmosquito larvae efficiently

and at low cost.

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