Here’s what you’re waiting for—two wonder chemicals with jawbreaking names that spell doom to insect pests
MOSQUITOES bad this summer?
Take heart, my friend, your days of slapping and scratching are numbered. The rescue squads from the laboratories are heading your way, armed with spray gun and chemical vial.
The spray guns are loaded with dichlorodiphenyltrichloroethane — DDT to you. One blast of this stuff will rid your house, cottage or tent of mosquitoes, flies and other insect pests and then keep them away for weeks. But since DDT’s been to war, this summer only dribbles are being made available for experimental civilian use.
The vials are charged with another jawbreaker starling with “d.” This is dimethyl phi halate, for which no one has yet coined a nickname. It’s a clear liquid which, when spread on your skin, keeps the varmints away for four hours. The services are getting all of it, too, but the civilians’ turn is coming.
While dimethyl phthalate repels insects, DDT kills them outright by poisoning their nerves. To gain an idea of the potency of this innocuous-seeming white powder, trade places for a moment with a mosquito or any other insect pest against which you cherish a special scunner.
On your first contact with any object sprayed with DDT solution you begin to exhibit a general lack of control. Perhaps you can fly, but you can’t walk. As the stuff takes hold, you lunge through the air in crazy loops and turns, crashing into objects in your path and açting like a toper in the latter stages of a New Year’s wingding. Then the DDT hits your central nervous system—you crash to the ground, paralysis sets in, and in a short time you expire.
That’s what happens to bugs which tangle with DDT. As a human, however, you needn’t be scared of it in the forms in which it will come to you.
Credit for the discovery of DDT goes to no modern researcher working with war necessity as the spur. A European, one Zeidler, threw the first batch together as a chemical curiosity in 1874, using chloral, sulphuric acid and monochlorobenzene as his main ingredients. More than 40 years later a Swiss dye manufacturer called Geigy stumbled on Zeidler’s notes as he was casting about for a mothproofing substance to add to his dyes. DDT proved effective beyond his wildest dreams.
Rediscovered, used with spectacular
results . against Colorado beetles that threatened the Swiss potato crop in 1937, the compound commended itself to the Allies as a valuable defensive weapon when war came.
Up to now DDT has been in such demand by the Allied Armies that the poor civilian has not even had a look at it. This year, however, with the collapse of Germany and the probable disposal of Canadian troops, under United States command, for the Pacific war, the entire output of DDT by Naugatuck Division, Dominion Rubber Company, Elmira, Ont., amounting to some 40 tons per month, is being allocated to different agencies within the Dominion for experimental purposes. If the war picture warrants it, according to A. M. W. Carter of the Pesticides Administration, a limited quantity of DDT may be available to civilians for home use within the next year.
In 'addition to the Elmira production centre, a plant is being set up at Shawinigan Palls, Que., by a subsidiary of Shawinigan Water and Power Company, for manufacture of the necessary chloral and monochlorobenzene. The Shawinigan plant will have sufficient capacity to meet all anticipated domestic needs.
Several hundred pounds have already been distributed in Canada for antibedbug and cockroach experiments, and many “bootleg” outfits, such as research labs, universities and private chemists with a supply of the ingredients on hand, are making a little for home use. Any chemist, given the materials, can make DDT in its crude form.
Very much like icing sugar in appearance, DDT Is soluble in most oils—kerosene, fuel oil and crude oil included—and in organicsolvents such as acetone, ethyl acetate and benzene. It will not dissolve in water. This is no great drawback—it means, for one thing, that rain or perspiration does not wash it away.
A barn spray, made of DDT dissolved in kerosene, is being put on the market later this year. Purely as a precautionary measure aimed at those who might drink it, wittingly or otherwise, it has been marked “Poison.” It is estimated that two sprayings of DDT, one in June and the other in August, will keep stables, barns, chicken coops and most farm buildings free from flies for an entire summer. You can see why the farmer is getting DDT first—with the whole of Europe to feed, he’s an important customer.
Well, you may say, I don’t douht that DDT is wonderful stuff, but what can it do for me? Here are some of the answers:
Your garments will come back from the cleaners already treated for moths. Washables treated with DDT solutions will be fatal to insects even after seven or eight tubbings. Around the sink a few squirts of DDT will
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discourage cockroaches from ever showing their noses. Spiders and houseflies will be as rare as peacocks. You will spray the mattresses with a DDT solution or blow a talcum-DDT mixture into cracks in the walJhoard and bedbugs, if present, w'ill he completely eradicated forat least six months. Your dog will thank you with a million tail wags for ridding him of tormenting fleas. The family car or plane will get a regular dusting with DDT while the oil is being changed, and woe to the wasp or fly who starts fooling around inside.
If you operate a theatre, hospital, meat plant or dairy, you will have cause to bless the names of Zeidler and Geigy.
Bug Battle in the Swamp
If you live in Ottawa you already have learned something of what DDT will do for you. The patients in the little Indian hospital of Coqualeetza in Sardis, B.C., probably also know. So, too, does part of Winnipeg. These places applied for, and obtained, a few pounds of DDT’ to use in their antimosq u i to ca mpa igns.
Inhabitants of Ottawa — Cabinet ministers, one dollar-a-year men and j plain taxpayers -might never have remarked the fact, hut, although the countryside around the Capital is ideal for the breeding of mosquitoes and ¡ black flies, very few of the pests actually penetrate into the city. For the past 18 years or so, the Federal District Commission, in a joint venture with surrounding municipalities, has engaged in a very active campaign of mosquito control.
In ordinary years the FDC use about 15,000 gallons of fuel oil in its program, with a hit of cresylie acid added for good measure. Twenty to 30 men are engaged for a month spraying swamps, creeks, ponds, sloughs and other breeding places in a strip roughly 10 miles long and five miles wide around the Capital. The results are usually excellent.
This year, however, only five or six men were available for the work. The Entomology Division of the Dominion Department of Agriculture proposed that the FDC use a DDT mixture in place of straight oil, and that they
spray according to the Division’s directions. Although it was only an experiment on a fairly large scale, it has turned out to be an acid test for DDT in mosquito control, since, even as the Division planned it, heavy rains were pelting down on the area.
The DDT spraying mixture, formulated under the guidance of Dr. C. R. Twinn, Entomologist of the Dominion Department of Agriculture, was made up of four pounds of DDT to 45 gallons of fuel oil. The spraying gang, carrying portable 2^¿-gallon pressure pumps on their backs, worked their way through the underbrush and swamps of the Ottawa suburbs, applying about two gallons of mixture to each acre of swamp.
Results, according to V. C. Askwith, Construction Engineer for the Federal District, have been more than satisfactory. In almost every case where treated water samples were tested for traces of mosquito larvae the findings were negative. In other respects also, the outcome has been remarkable. Instead of the 15,000 gallons usually employed at a total cost of $7,000, this year’s operations required only 2,000 gallons of oil at a complete cost of only one quarter the previous figure. Cost of the DDT used is negligible, according to the Commissioner, since such a small concentration is used, even though DDT costs about $1 a pound. Some 200 pounds have been used in all.
Ina year or so, every city in Canada may he able to inaugurate its own mosquito control program, and the pesky beasts may become a tribulation of the past. It all depends on the progress of the Pacific war. No DDT has been released in either the United States or Britain for other than experimental purposes.
. There have been some reports that DDT applied over large areas of land kills off many beneficial insects, as well as some birds, frogs and other creatures which do no harm; especially the honeybee, who spends his time making honey for you. These reports have some foundation in fact. DDT applied indiscriminately over large tracts might do more harm than good.
Don’t Upset Nature’s Applecart
Look at it the way E. H. Strickland of the University of Alberta sees it. Suppose you have an insect pest which is causing considerable harm to your trees or crops. You want to get rid of
him, so you apply DDT and kill him off completely. But in so doing, you are upsetting a very fine balance which Nature has set up between your pest and the parasite which preys on him. The parasite, a friend of yours, will starve to death. Then, a couple of years later, if the wind happens to be in the right direction, back comes the pest worse than ever, for you, obligingly, have rid him of his natural enemies.
“The place for DDT’s invaluable employment,” says Strickland, “is surely confined to small areas in homes, buildings, planes, gardens and orchards, where its use cannot seriously affect the ‘balance of Nature’ over large tracts of land.”
But we spend a lot of time at the lake in summer, you may say, and we’ve always had trouble there with flies. Junior almost gets eaten alive every time he goes to Boy Scout camp too. What, exactly, is being done to help us protect ourselves in the open?
A good question, but again you’ll be well looked after. Scientists in the U. S., Britain and Canada have done a lot of work in the search for repellent materials to keep flies away from troops on the march. Some of their findings rival those made about DDT. For example, there’s dimethyl phthalate. Before the war chemists knew it as a common plasticizer, a material mixed with brittle plastics to make them flexible. Now, in the form of liquids, ointments and dopes smeared on soldier’s legs, arms, faces and feet, a single application keeps flies away for at least four hours.
The British use dimethyl phthalate straight. American soldiers, and from now on Canadians as well, carry little two-ounce vials of dimethyl phthalate mixed with two other ingredients, Rutgers “612” and Indalone, in the proportions of three of the former to one each of the others.
Alone or mixed, it does wonders. According to scientists dimethyl phthalate, although completely odorless to humans, and looking for all the world like ordinary water, masks human body odors which are so attractive to flies and at the same time gives off an odor of its own which is distasteful to them. The combination is too much for the pests.
At present so much dimethyl phthalate is being used in plastic materials and insect repellents for the services that none is available to civilians. But there’ll come a day!
Besides the mosquito control experiments, a number of other projects involving the use of DDT are being carried out in different parts of Ontario and Quebec. Greatest of these, and incidentally the biggest forest insect experiment ever undertaken in North America, is being conducted around Sturgeon Lake, 80 miles north of Fort William. The object of this work, as of all forestry experiments involving DDT, is to try and halt the spread of the greatest menace Canadian or U. S. forests have ever encountered— the spruce hudworm.
The devastation caused by the spruce hudworm is simply tremendous. Starting out on a small forest patch in northern Quebec in 1909, the worm has worked his way westward and eastward until he now infests over 135,000 square miles of forest between Lake Nipigon in Ontario and the St. Maurice Valley in Quebec. The worm attacks the leaves of the trees, showing a special preference for balsam needles Trees w’hich shed their leaves eacl year are not usually killed, but foi evergreens this form of assault is lethal. A short time after the hudworm has
passed through a forest, nothing is left of many of these trees but dead hulks which will topple with the first big wind.
Planes Aid in Budworm Fight
The spruce budworm operations which began at Sturgeon Lake on May 15 are financed by the Ontario Government, and are being carried out under joint auspices of the Ontario Department of Lands and Forests, the RCAF and the Forest Insects Division of the Dominion Department of Agriculture. Four amphibian Canso flying boats of Eastern Air Command, complete with 5-man crews and supporting ground crew, are being used to spray 37 tons of DDT over upward of 80,000 acres of forest. In this area are miles and miles of trees whose needles have not yet been completely denuded by the blight. It is hoped that these trees can be saved.
J. J. de Gryse, head of the Forest Insects Division, has this to say: “From our observations we have concluded that the spruce budworm can be readily killed in its early stages by DDT. A few minutes after this spray is applied the larvae begin to fall down, and there is a heavy mortality among them. Of the over-all picture and the possible repercussions it is still too early to predict.”
Two other experiments on small but more exhaustive scales are being carried out at Kabonga Reservoir, Que., and Algonquin Park, Ont. The latter is a continuation of work carried out by planes last year. At Kabonga, 180 miles north of Ottawa, two square miles of very dense brush have been divided into 18 experimental plots, and, financed by the Quebec Lands and Forests, a private airplane is being employed to spread the mixtures.
H. G. Crawford, Dominion Entomologist, who toured the area recently in company with Dr. Lionel Daviault, Director, Forest Entomology of the Province of Quebec, provided an interesting side light to the main issue.
“Walking through the woods we were almost eaten alive by black flies and mosquitoes,” says Mr. Crawford. “Then the plane spraying DDT passed over, and an hour later nary a fly was to be seen. We sat down in one of the densest spots and never got a single bite.”
At this time it is still too early to evaluate the results of these three tests, but we can give some of the results of last year’s work. A group of scientists, composed of men from the Ontario Department of Lands and Forests, the
University of Toronto, the Royal Ontario Museum, and the Dominion Department of Agriculture, who studied the effects of spraying forests with DDT, came up with this information:
Birds suffer no ill effects whatsoever from DDT.
Foliage on some trees is seared a little, but this may be due to the solvent used rather than the DDT itself.
Mammals such as mice, chipmunks, beaver and deer are in no way affected, but very heavy concentrations of DDT might have some injurious effect on their reproductive organs.
Frogs, toads and snakes suffer considerably from DDT.
Crayfish, tadpoles, mollusks and dragonflies are somewhat damaged.
Although most fish are not bothered particularly by the presence of DDT, speckled trout often die from its effects, since they eat insects which might have succumbed to the nerve poison.
The honeybee is not harmed by DDT as much as was previously believed.
DDT as Orchard Guardian
At Vineland, in Ontario’s Niagara peninsula, W. A. Ross of the Dominion Agriculture Department has been corelating all the information obtained in Canada on the subject of DDT. His specialty, as one would imagine from his geographical location, is orchard pests. In his experiments during the last couple of years he has found many strange facts about the compound. For example, there are two species of asparagus beetle, both very much alike in outward appearance. Until now entomologists have had a very hard time trying to tell them apart. Now it’s easy. You sprinkle a little DDT around—one beetle drops and the other remains standing. Then there’s the codling moth, an apple pest if ever there was one. DDT knocks him off as easy as winking. However, and this is important, DDT also kills another little orchard dweller who usually feeds on a bug called the European red mite. But DDT has no effect whatever on the red mite. Result: a plague of red mites where none existed before.
Mr. Ross feels that DDT will inevitably be of great importance to fruit and vegetable growers once it has been thoroughly investigated.
One thing which can be stated without qualification—when that Swiss dyemaker went scouting for a moth discourager he really started something!