CORN-BORER Research Lays Foundation for Control of the Pest

When, in the fall of 1917, it was discovered that a dangerous alien insect enemy of that wonderful giant grass which Americans value highly as corn but which the rest of the world calls maize or mealies, had silently deployed its ravaging ranks throughout the fertile fields of the market gardens of suburban Boston, the announcement caused not a single ripple of interest on the surface of the ocean of finance. Now, however, after the lapse of a decade, and the expenditure of fully $15,000,000 in combat against this same pest, the financiers of agriculture, and indeed the whole business organization of the Corn Belt, stand on the qui vive for news regarding the progress of the fight against the European corn borer.

The story of that fight has been published; the actual weapons of combat and the telling way in which they are being employed have been abundantly described both in the daily press and in popular periodicals throughout the country, but the story of how these weapons were forged, and from whence came the basic knowledge which has since given corn growers the right to regard the corn borer as a foe that can be conquered, remains to be related.

After this intruder was discovered by Stuart Vinal, who died in 1918 as the direct result of his devotion to this problem, it was dispatched to Washington for identification; and, at the very moment that its dangerous character was confirmed, plans began evolving in the Bureau of Entomology of the Department of Agriculture for the laying of that foundation of research which constitutes the indispensable basis for all efficient insect-control work.

As a nucleus for such work, a tiny laboratory building was rented at Arlington, Mass., in the spring of 1918. Here began the first serious studies of the corn borer made in this country, and from this humble beginning has grown that fine research organization which since has become responsible for the accumulation of the vast array of tabulated information regarding the corn borer that even now points the way to ascendency over the pest.

Soon it was ascertained that the insect had come to America both from Italy and from Hungary, hidden away in broom corn imported from these countries for manufacture.  A search of their literature revealed that it was known there as a pest of maize, but, the publications regarding it were of rather fragmentary character. No complete account, was extant, and some of the published information seemed contradictory and confused in character. Through L. O. Howard, then chief of the Bureau of Entomology, the services of J. Jablonowski, official entomologist for the Kingdom of Hungary, were engaged to write a full account of the corn borer and its habits in his country and adjacent, territory. This he did in a very competent manner; and his manuscript, which later was abstracted -and mimeographed, proved invaluable as a source of suggestive information.

In 1919, after public interest in the pest had partially awakened and funds for more adequate research had become available, it was determined to attempt to introduce the parasitic enemies of the corn borer from Europe, as an aid to active control work. Since that time the collection and shipment to this country of many thousands of the beneficial insect parasites of the corn borer, comprising at least 12 species, has been accomplished.

Although the corn borer was discovered to be present in the east-central and western parts of New York in 1919, the major research studies of it were conducted for several years in eastern Massachusetts because the insect was very abundant there, not only in corn but in many other host plants which it did not attack in the more western regions. This condition afforded facilities for research which were not available elsewhere.

A branch laboratory was, however, established, first at Scotia, N. Y., near the location of the first infestation found in that State, but afterwards transferred to Silver Creek, in the corn-canning section of the same State, where it has since remained.

The small laboratory at Arlington soon became inadequate, and more spacious quarters were obtained in the same town. Here, during the period from 1920 to 1925, inclusive, the pioneer, basic, research work on this insect was accomplished. The reactions of the insect to heat, cold, and humidity were determined for the egg, larval, and pupal stages. The degree of fecundity of the adult was observed, and its powers of flight were demonstrated over the waters of Cape Cod Bay for a distance of some 20 miles. The ability of the borers to survive while submerged in either fresh or salt water for days at a time was shown, and their almost complete immunity from the effects of frost was demonstrated by freezing them and afterwards thawing them out and observing the erstwhile frozen corpses transform into healthy moths which laid eggs that produced voracious progeny.

Most important investigations to determine the plants affording potential food and shelter to the insect were conducted on a plat of ground donated for that purpose by a public-spirited citizen of the near-by town of Medford.  Among the plants thus tested were many standard varieties of corn, sorghum, including the sweet, grain, and broom varieties, cotton, sugar cane, small grains, including rice and millets, tobacco, garden vegetables, and flowering plants, and weeds almost without number.

The forage legumes were experimented with in great variety, including the clovers, alfalfa, soy beans, cowpeas, velvet beans, and many others.

Another line of research followed at this time was the testing of lights of various colors and intensities, to determine whether the moths could be lured to them and trapped. The results of this work were negative in all cases, but they furnished information that has proved invaluable in the last several years, when inventors and others, literally by hundreds, have approached the department with proposals to utilize trap lights in this impracticable way.

Various poisonous chemicals were tested as insecticides for the pest, including practically all of the standard arsenicals and many other poisons, but without any substantial success. In point of fact, much of the work of these years along all lines had negative results, but these served to clear the ground for subsequent work which gave results of the utmost utility.

It was in these years, too, that the first efforts toward mechanical and cultural control were initiated. The first experiments were undertaken to determine the effects of both spring and fall plowing on the corn borer, hidden at these seasons in the stalks, cobs, and stubble of corn. The first tests of the burying of stalks in compost or manure were made, and many futile attempts were made, with various apparatus, to dig out and burn the stubble above the surface of the ground.

The lines of promising procedure indicated by the research work of these early years are the ones which now are being followed successfully in the fight against the corn borer in the Corn Belt. As the insect grew more numerous in the region of the Great Lakes, it became possible to test in a large and practical way such simple methods of control as the plowing under of cornstalks, stubble, and débris, the breaking over of standing stalks with a pole or iron rail and the sub- sequent raking and burning of them. The last-named method, followed by the plowing under of the remaining débris, gave a control that was entirely satisfactory.

In the meantime additional field laboratories had been established at Sandusky, Ohio, and at Monroe, Mich., where the reaction of the corn borer to these environments was studied, and its parasites were reared and liberated to prey upon it, and thus eventually to aid the corn growers in their fight against the pest. Seven of these parasites have now been recovered from the field, a fact indicating that they have become successfully established; and although many years must elapse before material benefit can be expected from them, substantial aid may be hoped for in the end.

In order that this serious problem shall have the benefit of the most highly trained minds in the land, the department for the last three years has called annual conferences of eminent entomologists, agronomists, and other scientists, in Washington, to consider the complete program of corn-borer research for the ensuing year. Such meetings have been the source of material aid in obtaining complete cooperation of the States interested, and have elicited suggestions for supplementary lines of research that may prove of great value. One such development is the building in the summer of 1928 of two field cages, each of one acre in extent. These cages were erected over fields that had been treated for control by cultural methods, to ascertain how many moths would escape death in the clean-up process. The results in both cases indicate the substantial success of the treatments, and serve to clinch the argument in favor of plowing and other simple farm operations as the logical method of control now at hand.

Research is the foundation upon which is built the structure of all efficient insect-control work.