On the Bug Front

World War II is a boon to the bug armies. The minerals with which man has fought bugs for years-arsenic, copper, lead-are now needed for his war on his own kind. Carbon tetrachloride, ethylene dichloride and chloropicrin are withheld from insecticide manufacturers for the benefit of war materials. The phosphorus paste that used to kill cockroaches now goes into incendiary bombs. A group of six articles on the war against insects, in the current issue of Industrial & Engineering Chemistry, makes these facts plain.

There is one offensive that never ends: man's battle against insects. It is a fight against the grasshoppers, the Mormon crickets, the boll weevils, the chinch bugs, the now doubly despised Japanese beetles and other pests that do two-billion-dollar damage every year in the U.S. alone; against flies, lice, roaches, mosquitoes and other infamous bugs that carry disease. Entomologists estimate that the U.S. harbors 7,000 species of insect pests. Said Entomologist Stephen Alfred Forbes of Illinois: "The struggle between man and insects began before the dawn of civilization . . . and will continue, no doubt, as long as the human race endures. It is due to the fact that both men and certain insect species constantly want the same things at the same time. ... Its long continuance is due to the fact that the contestants are so equally matched."

There are some good insecticides that can be made from plants, of which one is rotenone. But no more rotenone comes from derris root in the East Indies, which used to supply more than half the U.S. needs. About 40% of the rotenone normally used in the U.S. comes from South America. Intensive cultivation could step this up to 60%; but the problem of finding shipping space and getting the ships past Axis submarines would remain.

Pyrethrum powder, a standard insecticide which is made from a certain chrysanthemum plant, used to be imported largely from Japan. In recent years coffeegrowers in Britain's Kenya Colony in Africa have cultivated the plant, now grow enough for their own use and the whole U.S. besides-if the U.S. can get it. Chemists, however, have discovered ways to stretch the pyrethrum supply by adding "synergistic" compounds-sesamin from sesame oil and asarinin from the southern prickly-ash bark-which make a more poisonous blend than pyrethrum alone.

China has been combed for plants poisonous to insects by Dr. Shin Foon Chiu, Cornell graduate. One of his finds tested at Cornell by Dr. Roy Hansberry is Millettia pachycarpa, which bears seeds as big as small walnuts. Dr. Hansberry found Millettia to be as effective as rotenone dust, but the plant is not yet grown in quantity in the U.S.

Of the synthetic insecticides, one of the most promising is phenothiazine, which is made from a coal-tar derivative and sulfur. This chemical is deadly to the codling moth which costs U.S. applegrowers nearly $18,000,000 a year. Early failures in field tests with phenothiazine were found to be due to the size of the particles. They were too big. Later tests with more finely ground phenothiazine turned out much better.

Insecticides are now rationed, like any other scarce commodity. Farmers come first, hospitals next. As usual, the ordinary householder comes last. To householders pestered by roaches and flies, a WPB official offered this advice: "Hit them with a fly swatter like your grandmother did. This is war!" Fly swatters, wheiher made of rubber or metal, will soon be scarce, too (TIME, April 13).

This file is automatically generated by a robot program, so reader's discretion is required.