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1948-49 Theatre Catalog, 7th Edition, Page 249 (238)

1948-49 Theatre Catalog, 7th Edition
1948-49 Theatre Catalog
1948-49 Theatre Catalog, 7th Edition, Page 249
Page 249

1948-49 Theatre Catalog, 7th Edition, Page 249

himself with the principal kinds of insecticides, their characteristics, and the methods for applying them, the drive-in operator will be able to cope intelligently with a problem that will be always with him.


Whether the operator services his drive-in theatre personally, or calls upon an outside insecticide specialist and applicator, he will be guided in his final choice of material by a number of factors. Cost of the insecticide will certainly be one of the primary considerations. Over-all effectiveness and killing power of the chemical will have to be recognized. And there are less obvious questions to be answered. How long will the killing and repellent power last after the insecticide is first sprayed into the air? How will over-spray affect neighboring farms or other personal property beyond drive-in limits? Does it leave a residue that is poisonous to man or animals breathing the saturated air, or eating crops touched by the air-borne particles? Is its residue poisonous to surrounding soil? Is the applicator susceptible to poisoning when handling the chemical?

These questions and related ones point up the important requisites for an ideal insecticide-that it be an all-powerful killer of insects and at the same time be harmless to man, beast and plants. Thatls a tough combination of conditions to satisfy but, by and large, the agricultural chemical companies have come very close to achieving the impossible in this field. With the many potent insecticides now at his command, the open-air theatre man should be able to out-maneuver and out-guess even the most vicious insect hoodlums and do it without unbalancing the budget. The insecticides described below have been included on the basis of their ability to deal roughly with mosquitoes, dies, moths, and fiower and plant pests. Both recently developed and old-established insect-killers have been listed. When they are known, possible dangers or disadvantages in the usage of an insecticide are mentioned. Methods of application are described in a later section.


A powerful, all-purpose insecticide was recently developed by the American Cyanamid Company. THIOPHOS-3422* or O, O-Diethyl O, p-Nitrophenyl Thiophosphate, to give it its correct chemical nameewas tested in 1947 by approximately 165 entomologists in 75 Federal and State Experiment Stations and their investigations disclosed an amazingly wide range of effectiveness for the new insect-killer.

For one thing, THIOPHOS-3422 is five to twenty-five times more potent than DDT, depending on the insect to be eliminated. At the same time it is compatible with DDT and, if desired, can be used in cover sprays with DDT. It is also compatible with wettable and dusting sulfurs, insoluble coppers, benzine hexachloride, rotenone, pyrethrum and lead arsenate. The compound is quite stable to hydrolysis in normal waters

and is not readily destroyed by oxidation.

'THIOPHOS-3422 is said to be effective against a wider range of insects (including flies, moths, and mosquitoes), mites and other lower invertebrates than any other chemical for the purpose. In fact, no species of insect has been found, in laboratory tests, that can resist its toxic action at concentrations now in use with established insecticides. Aphids are very easily controlled with THIOPHOS-3422 at economical dosages. In mosquito-larval control, the insecticide is said to be about 20 times more effective than DDT, takes less material to do the job, and is less likely to kill fish.

The chemical in technical grade is a liquid. After formulation into wettable powders it can be used as a spray. It can also be formulated for use as a dust. Spray formula for most conventional uses amounts to one pound of 25 percent Wettable powder per 100 gallons of water.

From experimental tests at concentrations needed for effective control of injurious insects, it appears that THIOPHOS-3422 insecticide does not produce plant injury. In fact, it is evident that there is a rather Wide margin between insecticidal action and plant injury. It is safe to use on roses, Chrysanthemums, carnations, snapdragons, and practically all other greenhouse plants.

THIOPHOS-3422 does not create a residue problem since present evidence indicates that it remains effective for 5 to 12 days outdoors and disappears from crops almost entirely in 10 to 12 days, so that neither animals nor human beings eating the crops are harmed. On the other hand, it does seem to last long enough to kill delayed arrivals of some insects and to affect young stages of insects hatched from recently placed

eggs Precautions should be observed in handling the material since it is definitely toxic. It can be absorbed through the skin, and prolonged exposure to a spray or dust could prove harmful. If the insecticide is to be handled for a long time, the operator, to be absolutely safe, should wear a respirator.


With the discovery of methoxychlor, the active ingredient in ffMarlate", DuPont chemists have developed an insecticide that is quick-acting, lasts a long time and is entirely safe to use. Manufactured as a fine white powder for use in dusts or in water suspensions for spray applications, "Marlate" controls many kinds of insects, brings death to many bugs. It kills fiies and mosquitoes more quickly than does DDT by having the added advantage of a knockdown effect on these obnoxious common pests. Its killing power lasts several weeks, and it can be u5ed with little danger to people, domestic animals (a herd of succulent beefsteaks may be grazing peacefully in an adjoining meadow) and plants. Tests on flowerseroses, for exampleeshow remarkably little plant injury, even after relatively heavy applications. And no toxic residue is left on food products.

Methoxychlor is a slightly different form or analog of DDT. Although its insecticidal properties were discovered during the war years, other insecticides then were receiving the lions share of attention. Methoxychlor was forced to hide its time until it had been proved safe to use by intensive laboratory and field tests. lfMarlate" (the trade name of methoxychlor) is compatible with most common insecticides.


One of the most promising of the newer insecticides is Chlordane, applied as a dust or a spray. With this chemical, ticks have been controlled in wooded places, as along roadsides, by an application of 1 pound per acre. The larval of the Japanese beetle working on the roots of plants, especially grass, have been controlled by an application of 110 pounds per acre. In addition, Chlordane has controlled the mole crickets attacking golf greens in some of the Southern states. Chlordane has given phenomenal control of grasshoppers by the use of 1/2 to 1 pound of active ingredients per acre, applied as a dust or a spray. Residual effect of 11 to 16 days was also obtained. In some instances, residual properties are said to be effective for as long as five weeks after application. Final recommendations have not yet been established for all insect pests.

It is definitely known that this inSecticide can be used with little or no injury to plant life. In fact, there have been reports of increased growth in plants after a Chlordane treatment but the biological explanation for this stimulation is not known.

Chlordaneis toxicity to human beings is roughly equal to DDTls, considered on an equal weight basis. However, since Chlordane formulations are usually of lower concentration than those of DDT, the chances for ill effects to the applie cator are considerably reduced.


The insecticidal use of DDT, or dichlorodiphenyltrichloroethane, was made in 1939 by Dr. Paul Mueller of the Geigy Drug Industries, Basle, Switzerland. In 1948 Dr. Mueller won the Nobel prize in medicine 'for his discovery.

In its pure form, DDT is seldom used as an insecticide. Most frequently it is dissolved and applied as a spray or mixed with a powder; and applied as a dust or a water spray. In concentrations of 2% or 3%, DDT has been effectively applied as a fog. The fog can be blown great distances and is quickly applied in such open-air amusement centers as stadiums, parks and drive-in theatres to free them of flies, mosquitoes, gnats, sandfiies and other undesirable creae tures.

DDTls toxicity to human beings is slight. In 1945, Food and Drug and Cosmetic Act Trade Correspondence stated that "No question is raised concerning the use of DDT on such fruits as apples and pears since it is less toxic than the other commonly used insecticides for these crops, such as lead arsenate and cryolite . . . For the present, the Food and Drug Administration will not take action against apples and pears contain THEATRE CATALOG 1948-49
1948-49 Theatre Catalog, 7th Edition, Page 249