NEW POISON FOR INSECTS

New Zealand Herald, Volume LXIX, Issue 21076, 9 January 1932, Page 7 (Supplement)

NEW POISON FOR INSECTS

AMERICAN EXPERIMENTS. A jungle poison known as rotenone is America's newest weapon against destructive insects. Thirty times as deadly to what the Americans call -" bugs," as arsenate of lead, tho commonest insecticide, it is already, being tested successfully in tho field against codlin moths, European corn borers, and Mexican bean beetles. For all its power it is declared to bo harmless to man. Its discovery is hailed as one of the most important victories yet won in the war on insect pests. Insects cost the lives of 75,000 Americans, and destroy more than £180,000,000 worth of produce each year. Popular Science states that the war against them is being waged on many fronts, scattered through tho United States. At Chicago a death chamber is executing flies so that new poisons to kill them may bo tested. A "model insectary "at the University of California breeds dangerous insects, for study, behind barred doors. And at-Silver Springs a small band of experimenters of the United States Department of Agriculture has just found a new ally in rotenone. It is hoped that this new weapon may rout the insect liordo for over. Science and exploration combined to reveal it. First the experimenters in the Maryland laboratory devised a way to test tho strength of any poison. Measured doses were fed to silkworms on poison sandwiches made of discs cut from mulberry leaves. Weighing the silkworm and tho amount of poison he ato showed just how much poison would kill how much " bug." Tho exports compared concoctions from all over the world. It was to the South American Indian that they went for rotenone, with which the natives of the Amazon catch fish. Crushing the roots of a tropical plant called cube (pronounced coo-bay), they extract the poison and dump it into a flowing stream. Even so greatly diluted, tho poison stupefies all fish nearby, Indians gather the fish that float to the surface and cat them, apparently without harm from the poison. The men at Silver Springs obtained a small quantity of rotenone and tried it on silkworms. Their greatest hopes were exceeded in tho tests, which showed that a single ounce of the poison would kill ten tons of insects. Unlike lead arsenate and other common poisons, it was entirely harmless to human beings. At present rotenone costs £2 to £4 a pound—too much for the average farmer. But plans are being made to grow it on a largo scale, possibly in the Virgin Islands. A second stronghold of America's insect fighters is the model insectary just opened at the University of California. There the most dangerous insect pests known to orango growers of western America are raised in locked rooms. Even the ventilating system is screened to prevent the ruin that would follow their escape. Meanwhile their habits are studied, and insect parasites brought from far countries are tested against them, to learn ' how to combat them on the ranches. Flies are the " public enemies " against which a research organisation of Chicago is concentrating its attack. Thousands of the disease-carriers are bred daily, to be put to death in a novel fly death chamber by various insecticides under test. So far the most effective fly poison found lias been an extract prepared from dried and compressed flowers of the Pyrethum, a chrysanthemum from Japan. Meanwhile Government " bug " fighters at the North Dakota Agricultural College have even gone out into the great outdoors to combat the common fly. DECAY IN FRUIT CARGOES. In an attempt to find out why fruit decays on the voyage from Australia to England, experts of the British Government's Fruity Research Station built a land fruit ship. This model reproduces conditions on a fruit vessel. Cases of apples are placed within the hold and thermometers indicate, in a laboratory overhead, the temperature in each case. Thus scientists will determine the temperature at which the fruit is least likely to spoil while it is on its long voyage. DEATH TO GRASSHOPPERS. A farmer in Nebraska, United States, this year saved his crops when they were menaced by grasshoppers by building a portable electric chair, which killed them by the bushel as it was hauled through the fields by a tractor. The insect destroyer consisted of a system of wires on a wooden frame and connected to a battery with step-up coils to increase the voltage. The wire frame was mounted on the front of an automobile or tractor, and dealt out swift death to the pests.