After careful investigation it was concluded that the leaf-hopper had been introduced in Hawaii in new varieties of seed cane imported from Australia, and, as the hopper was not doing material damage on the plantations in Australia, the inference was that it must be controlled there by its natural enemy. The chief of the Department of Entomology was sent to London. There in the archives of the British Museum he found a full description of the leaf-hopper and that its native habitat was Queensland, Australia. On his return to Hawaii, entomologists were sent to Australia and the search for the enemy of the hopper began.
LEAF-HOPPER (GREATLY MAGNIFIED)
SUGAR CANE
For weeks the entomologists virtually lived in the cane fields, undergoing extreme privations, but at last their faithfulness was crowned with success. Several species of parasites that kept the Queensland leaf-hopper in check were discovered, and later on more were found in the islands of Fiji. These tiny creatures as a rule were invisible to the naked eye and could only be seen with the aid of a powerful magnifying glass. All of these insects were parasites either of the leaf-hopper or its eggs. Two of them were particularly efficacious. One, quicker in movement than the hopper, caught it unawares and attached itself to the hopper’s body much in the same way that a mosquito does to a human being. After catching it, the parasite would sting the hopper and lay an egg in its body. In a few days a young parasite was hatched from the egg, and so ravenous was this young insect that it devoured the hopper in a short time and then sought a fresh victim in which to lay its eggs.
The other insect was even more effective. It liked the hoppers’ eggs and for a long time found plenty in Hawaii to stay its appetite. As soon as the leaf-hopper laid its eggs in the cane, this particular insect would appear and lay its eggs in the eggs of the leaf-hopper. When the little enemies hatched out, they fed on the hoppers’ eggs and in turn laid their eggs in the eggs of the hopper. It came to pass that the hoppers, attacked by the parasite on the one hand and by the enemy on the other, rapidly dwindled in number until only a few remained, and these not enough to do material damage. As the hoppers and their eggs diminished, so did the parasite and the enemy, for the latter could live on insect food only.
How the scientists collected these tiny animalcules, kept them alive, transported them thousands of miles across the ocean, bred them in Hawaii and saved the Hawaiian sugar industry, reads like a romance.
The study of entomology is extremely interesting and the every-day business man rarely understands its importance. The finding, breeding and distribution of parasites of insect pests vitally affects the world’s food supply. The entomological name of the leaf-hopper family is Hemiptera, and Dr. Sharp, an authority on the subject, has said: “There is probably no order of insects that is so directly connected with the welfare of the human race as the hemiptera; indeed if anything were to exterminate the enemies of hemiptera, we ourselves should probably be starved in the course of a few months.”
It has been estimated by competent authority that the damage done in the world each year by the hemiptera, in spite of all their parasites, is conservatively $600,000,000. Were it not for the parasites, it would only be a year or two at most before every green leaf and spear of grass would disappear from the face of the earth. The direct influence of the practical application of this science to the production of sugar is readily apparent.