National Geographic : 1941 Aug
Our Insect Fifth Column Alien Enemies Take Steady Toll of Food, Trees, and Treasure by Boring from Within BY FREDERICK G. VOSBURGH T HE man in the blue sedan was indig nant. Here he was, breezing along on a nice Sunday afternoon when all of a sudden a fellow in uniform had to stop him with the query, "Any plants or flowers in the car?" What possible difference could it make, fumed the motorist. What if he had bought a little shrubbery a few miles back and let the kids pick a handful of wild flowers. A potted plant wasn't a bomb and a bouquet of black-eyed-susans never killed anybody . . . True, there was no danger of fatal results. Yet that harmless-looking plant or handful of flowers might harbor an insect pest that would kill more trees than a forest fire or destroy more food than a whole "stick" of bombs. Committing their ceaseless sabotage in sev eral States are such dangerous insect "fifth columnists" as the gypsy moth, European corn borer, and Japanese beetle, whose spread into distant areas would be a major calamity. The object of the roadside inspections is to stop or slow the advance of alien insect enemies that have gained a foothold in this country. These foreigners are often most damaging be cause they have left behind their natural foes and can reproduce in tremendous numbers. Nine species alone, pictured here in color, affect the food, clothing, shelter, and incomes of millions-including the man in the blue sedan, whether he knows it or not. Other insects strike at man's health or attack his domestic animals. Government entomologists figure that in sects cost the country over $1,600,000,000 a year, or the equivalent of the services of a million men. Mosquitoes head the list, with the cotton boll weevil second. Then come the versatile corn earworm (page 234), the housefly, and the rice weevil which spoils cereals. An annual tribute of over 22 million dollars is exacted in the United States alone by the cosmopolitan clothes moths, and nearly double that sum by our native termites. Land of Opportunity-for Insects, Too Of the fifty worst insect pests in the United States, about a third have come from other countries, for human immigrants are not the only ones who have found this broad, rich nation a land of opportunity. Despite the most careful quarantine, sev eral new pests have entered in recent years and others have greatly extended their range. For example, when the first World War broke out the United States had not yet known the attack of the destructive Japanese beetle (Color Plate IV). The corn borer, now as far west as Wisconsin, was getting a foot hold in fields around Boston, its presence not even suspected (Plate III). Newest major menace is the South American white-fringed beetle, first discovered in this country five years ago and now attacking crops in four Gulf States (Plate VII). Spreading with the slow, persistent patience of Mother Nature herself, mere fluttering moths, feeble flies, and beetles that crawl but a few yards in a lifetime have crossed the wid est oceans. They come as stowaways on ships; nowadays even in airplanes.* They ride here hidden in straw, in a cargo of bones for fer tilizer, in plants or flowers which seemed so harmless to the man in the blue sedan. "Plant Ellis Island" Bars Undesirables At the "plant Ellis Island" in Hoboken, New Jersey, and forty other stations on our sea and land borders, thousands of undesirables are constantly being intercepted (pages 230, 233, and 248). They range from the tiny worms called nematodes to a two-foot snake which slithered out of a case of South American orchids last October. Exotic pests turn up where least expected. Alert inspectors of the Bureau of Entomology and Plant Quarantine found elm bark beetles, which carry the dread Dutch elm disease, in the wood of a crate containing English china. Larvae of a small injurious moth were found in a string of beads made of seeds from Italy. Against the country's quarantine wall beats a heavy tide of potential invaders, for there are estimated to be in the world some 20,000 * The malaria-carrying mosquito Anopheles gambiae, recently discovered in Brazil, is believed to have reached there in an airplane or fast ship from Africa. It is a particular menace because it lives close to man and makes a most effective carrier. Mosquitoes, not included in this article, will be the subject of a later color-illustrated presentation in the NATIONAL GEO GRAPHIC MAGAZINE. Another will include locusts.