Silent Spring

by Rachel Carson

  Just how sound were these claims? The statements made by Department witnesses seeking appropriations were not in accord with those contained in key publications of the Agriculture Department. The 1957 bulletin Insecticide Recommendations ... for the Control of Insects Attacking Crops and Livestock did not so much as mention the fire ant—an extraordinary omission if the Department believes its own propaganda. Moreover, its encyclopedic Yearbook for 1952, which was devoted to insects, contained only one short paragraph on the fire ant out of its half-million words of text.

  Against the Department's undocumented claim that the fire ant destroys crops and attacks livestock is the careful study of the Agricultural Experiment Station in the state that has had the most intimate experience with this insect, Alabama. According to Alabama scientists, "damage to plants in general is rare." Dr. F. S. Arant, an entomologist at the Alabama Polytechnic Institute and in 1961 president of the Entomological Society of America, states that his department "has not received a single report of damage to plants by ants in the past five years ... No damage to livestock has been observed." These men, who have actually observed the ants in the field and in the laboratory, say that the fire ants feed chiefly on a variety of other insects, many of them considered harmful to man's interests. Fire ants have been observed picking larvae of the boll weevil off cotton. Their mound-building activities serve a useful purpose in aerating and draining the soil. The Alabama studies have been substantiated by investigations at the Mississippi State University, and are far more impressive than the Agriculture Department's evidence, apparently based either on conversations with farmers, who may easily mistake one ant for another, or on old research. Some entomologists believe that the ant's food habits have changed as it has become more abundant, so that observations made several decades ago have little value now.

  The claim that the ant is a menace to health and life also bears considerable modification. The Agriculture Department sponsored a propaganda movie (to gain support for its program) in which horror scenes were built around the fire ant's sting. Admittedly this is painful and one is well advised to avoid being stung, just as one ordinarily avoids the sting of wasp or bee. Severe reactions may occasionally occur in sensitive individuals, and medical literature records one death possibly, though not definitely, attributable to fire ant venom. In contrast to this, the Office of Vital Statistics records 33 deaths in 1959 alone from the sting of bees and wasps. Yet no one seems to have proposed "eradicating" these insects. Again, local evidence is most convincing. Although the fire ant has inhabited Alabama for 40 years and is most heavily concentrated there, the Alabama State Health Officer declares that "there has never been recorded in Alabama a human death resulting from the bites of imported fire ants," and considers the medical cases resulting from the bites of fire ants "incidental." Ant mounds on lawns or playgrounds may create a situation where children are likely to be stung, but this is hardly an excuse for drenching millions of acres with poisons. These situations can easily be handled by individual treatment of the mounds.

  Damage to game birds was also alleged, without supporting evidence. Certainly a man well qualified to speak on this issue is the leader of the Wildlife Research Unit at Auburn, Alabama, Dr. Maurice F. Baker, who has had many years' experience in the area. But Dr. Baker's opinion is directly opposite to the claims of the Agriculture Department. He declares: "In south Alabama and northwest Florida we are able to have excellent hunting and bobwhite populations coexistent with heavy populations of the imported fire ant ... in the almost 40 years that south Alabama has had the fire ant, game populations have shown a steady and very substantial increase. Certainly, if the imported fire ant were a serious menace to wildlife, these conditions could not exist."

  What would happen to wildlife as a result of the insecticide used against the ants was another matter. The chemicals to be used were dieldrin and heptachlor, both relatively new. There was little experience of field use for either, and no one knew what their effects would be on wild birds, fishes, or mammals when applied on a massive scale. It was known, however, that both poisons were many times more toxic than DDT, which had been used by that time for approximately a decade, and had killed some birds and many fish even at a rate of 1 pound per acre. And the dosage of dieldrin and heptachlor was heavier—2 pounds to the acre under most conditions, or 3 pounds of dieldrin if the white-fringed beetle was also to be controlled. In terms of their effects on birds, the prescribed use of heptachlor would be equivalent to 20 pounds of DDT to the acre, that of dieldrin to 120 pounds!

  Urgent protests were made by most of the state conservation departments, by national conservation agencies, and by ecologists and even by some entomologists, calling upon the then Secretary of Agriculture, Ezra Benson, to delay the program at least until some research had been done to determine the effects of heptachlor and dieldrin on wild and domestic animals and to find the minimum amount that would control the ants. The protests were ignored and the program was launched in 1958. A million acres were treated the first year. It was clear that any research would be in the nature of a post mortem.

  As the program continued, facts began to accumulate from studies made by biologists of state and federal wildlife agencies and several universities. The studies revealed losses running all the way up to complete destruction of wildlife on some of the treated areas. Poultry, livestock, and pets were also killed. The Agriculture Department brushed away all evidence of damage as exaggerated and misleading.

  The facts, however, continue to accumulate. In Hardin County, Texas, for example, opossums, armadillos, and an abundant raccoon population virtually disappeared after the chemical was laid down. Even the second autumn after treatment these animals were scarce. The few raccoons then found in the area carried residues of the chemical in their tissues.

  Dead birds found in the treated areas had absorbed or swallowed the poisons used against the fire ants, a fact clearly shown by chemical analysis of their tissues. (The only bird surviving in any numbers was the house sparrow, which in other areas too has given some evidence that it may be relatively immune.) On a tract in Alabama treated in 1959 half of the birds were killed. Species that live on the ground or frequent low vegetation suffered 100 per cent mortality. Even a year after treatment, a spring die-off of songbirds occurred and much good nesting territory lay silent and unoccupied. In Texas, dead blackbirds, dickcissels, and meadowlarks were found at the nests, and many nests were deserted. When specimens of dead birds from Texas, Louisiana, Alabama, Georgia, and Florida were sent to the Fish and Wildlife Service for analysis, more than 90 per cent were found to contain residues of dieldrin or a form of heptachlor, in amounts up to 38 parts per million.

  Woodcocks, which winter in Louisiana but breed in the North, now carry the taint of the fire ant poisons in their bodies. The source of this contamination is clear. Woodcocks feed heavily on earthworms, which they probe for with their long bills. Surviving worms in Louisiana were found to have as much as 20 parts per million of heptachlor in their tissues 6 to 10 months after treatment of the area. A year later they had up to 10 parts per million. The consequences of the sublethal poisoning of the woodcock are now seen in a marked decline in the proportion of young birds to adults, first observed in the season after fire ant treatments began.

  Some of the most upsetting news for southern sportsmen concerned the bobwhite quail. This bird, a ground nester and forager, was all but eliminated on treated areas. In Alabama, for example, biologists of the Alabama Cooperative Wildlife Research Unit conducted a preliminary census of the quail population in a 3600-acre area that was scheduled for treatment. Thirteen resident coveys—121 quail—ranged over the area. Two weeks after treatment only dead quail could be found. All specimens sent to the Fish and Wildlife Service for analysis were found to contain insecticides in amounts sufficient to cause their death. The Alabama findings were duplicated in Texas, where a 2500-acre area treated with heptachlor lost all of its quail. Along with the quail went 90 per cent of
the songbirds. Again, analysis revealed the presence of heptachlor in the tissues of dead birds.

  In addition to quail, wild turkeys were seriously reduced by the fire ant program. Although 80 turkeys had been counted on an area in Wilcox County, Alabama, before heptachlor was applied, none could be found the summer after treatment—none, that is, except a clutch of unhatched eggs and one dead poult. The wild turkeys may have suffered the same fate as their domestic brethren, for turkeys on farms in the area treated with chemicals also produced few young. Few eggs hatched and almost no young survived. This did not happen on nearby untreated areas.

  The fate of the turkeys was by no means unique. One of the most widely known and respected wildlife biologists in the country, Dr. Clarence Cottam, called on some of the farmers whose property had been treated. Besides remarking that "all the little tree birds" seemed to have disappeared after the land had been treated, most of these people reported losses of livestock, poultry, and household pets. One man was "irate against the control workers," Dr. Cottam reported, "as he said he buried or otherwise disposed of 19 carcasses of his cows that had been killed by the poison and he knew of three or four additional cows that died as a result of the same treatment. Calves died that had been given only milk since birth."

  The people Dr. Cottam interviewed were puzzled by what had happened in the months following the treatment of their land. One woman told him she had set several hens after the surrounding land had been covered with poison, "and for reasons she did not understand very few young were hatched or survived." Another farmer "raises hogs and for fully nine months after the broadcast of poisons, he could raise no young pigs. The litters were born dead or they died after birth." A similar report came from another, who said that out of 37 litters that might have numbered as many as 250 young, only 31 little pigs survived. This man had also been quite unable to raise chickens since the land was poisoned.

  The Department of Agriculture has consistently denied livestock losses related to the fire ant program. However, a veterinarian in Bainbridge, Georgia, Dr. Otis L. Poitevint, who was called upon to treat many of the affected animals, has summarized his reasons for attributing the deaths to the insecticide as follows. Within a period of two weeks to several months after the fire ant poison was applied, cattle, goats, horses, chickens, and birds and other wildlife began to suffer an often fatal disease of the nervous system. It affected only animals that had access to contaminated food or water. Stabled animals were not affected. The condition was seen only in areas treated for fire ants. Laboratory tests for disease were negative. The symptoms observed by Dr. Poitevint and other veterinarians were those described in authoritative texts as indicating poisoning by dieldrin or heptachlor.

  Dr. Poitevint also described an interesting case of a two-month-old calf that showed symptoms of poisoning by heptachlor. The animal was subjected to exhaustive laboratory tests. The only significant finding was the discovery of 79 pans per million of heptachlor in its fat. But it was five months since the poison had been applied. Did the calf get it directly from grazing or indirectly from its mother's milk or even before birth? "If from the milk," asked Dr. Poitevint, "why were not special precautions taken to protect our children who drank milk from local dairies?"

  Dr. Poitevint's report brings up a significant problem about the contamination of milk. The area included in the fire ant program is predominantly fields and croplands. What about the dairy cattle that graze on these lands? In treated fields the grasses will inevitably carry residues of heptachlor in one of its forms, and if the residues are eaten by the cows the poison will appear in the milk. This direct transmission into milk had been demonstrated experimentally for heptachlor in 1955, long before the control program was undetaken, and was later re-potted for dieldrin, also used in the fire ant program.

  The Department of Agriculture's annual publications now list heptachlor and dieldrin among the chemicals that make forage plants unsuitable for feeding to dairy animals or animals being finished for slaughter, yet the control divisions of the Department promote programs that spread heptachlor and dieldrin over substantial areas of grazing land in the South. Who is safeguarding the consumer to see that no residues of dieldrin or heptachlor are appearing in milk? The United States Department of Agriculture would doubtless answer that it has advised farmers to keep milk cows out of treated pastures for 30 to 90 days. Given the small size of many of the farms and the large-scale nature of the program—much of the chemical applied by planes—it is extremely doubtful that this recommendation was followed or could be. Nor is the prescribed period adequate in view of the persistent nature of the residues.

  The Food and Drug Administration, although frowning on the presence of any pesticide residues in milk, has little authority in this situation. In most of the states included in the fire ant program the dairy industry is small and its products do not cross state lines. Protection of the milk supply endangered by a federal program is therefore left to the states themselves. Inquiries addressed to the health officers or other appropriate officials of Alabama, Louisiana, and Texas in 1959 revealed that no tests had been made and that it simply was not known whether the milk was contaminated with pesticides or not.

  Meanwhile, after rather than before the control program was launched, some research into the peculiar nature of heptachlor was done. Perhaps it would be more accurate to say that someone looked up the research already published, since the basic fact that brought about belated action by the federal government had been discovered several years before, and should have influenced the initial handling of the program. This is the fact that heptachlor, after a short period in the tissues of animals or plants or in the soil, assumes a considerably more toxic form known as heptachlor epoxide. The epoxide is popularly described as "an oxidation product" produced by weathering. The fact that this transformation could occur had been known since 1952, when the Food and Drug Administration discovered that female rats, fed 30 parts per million of heptachlor, had stored 165 parts per million of the more poisonous epoxide only 2 weeks later.

  These facts were allowed to come out of the obscurity of biological literature in 1959, when the Food and Drug Administration took action which had the effect of banning any residues of heptachlor or its epoxide on food. This ruling put at least a temporary damper on the program; although the Agriculture Department continued to press for its annual appropriations for fire ant control, local agricultural agents became increasingly reluctant to advise farmers to use chemicals which would probably result in their crops being legally unmarketable.

  In short, the Department of Agriculture embarked on its program without even elementary investigation of what was already known about the chemical to be used—or if it investigated, it ignored the findings. It must also have failed to do preliminary research to discover the minimum amount of the chemical that would accomplish its purpose. After three years of heavy dosages, it abruptly reduced the rate of application of heptachlor from 2 pounds to 1¼ pounds per acre in 1959; later on to ½ pound per acre, applied in two treatments of ¼ pound each, 3 to 6 months apart. An official of the Department explained that "an aggressive methods improvement program" showed the lower rate to be effective. Had this information been acquired before the program was launched, a vast amount of damage could have been avoided and the taxpayers could have been saved a great deal of money.

  In 1959, perhaps in an attempt to offset the growing dissatisfaction with the program, the Agriculture Department offered the chemicals free to Texas landowners who would sign a re-lease absolving federal, state, and local governments of responsibility for damage. In the same year the State of Alabama, alarmed and angry at the damage done by the chemicals, refused to appropriate any further funds for the project. One of its officials characterized the whole program as "ill advised, hastily conceived, poorly planned, and a glaring example of riding roughshod over the responsibilities of other public and private agencies." Despite the lack of state funds, federal money continued to trickle
into Alabama, and in 1961 the legislature was again persuaded to make a small appropriation. Meanwhile, farmers in Louisiana showed growing reluctance to sign up for the project as it became evident that use of chemicals against the fire ant was causing an upsurge of insects destructive to sugarcane. Moreover, the program was obviously accomplishing nothing. Its dismal state was tersely summarized in the spring of 1962 by the director of entomology research at Louisiana State University Agricultural Experiment Station, Dr. L. D. Newsom: "The imported fire ant 'eradication' program which has been conducted by state and federal agencies is thus far a failure. There are more infested acres in Louisiana now than when the program began."

  A swing to more sane and conservative methods seems to have begun. Florida, reporting that "there are more fire ants in Florida now than there were when the program started," announced it was abandoning any idea of a broad eradication program and would instead concentrate on local control.

  Effective and inexpensive methods of local control have been known for years. The mound-building habit of the fire ant makes the chemical treatment of individual mounds a simple matter. Cost of such treatment is about one dollar per acre. For situations where mounds are numerous and mechanized methods are desirable, a cultivator which first levels and then applies chemical directly to the mounds has been developed by Mississippi's Agricultural Experiment Station. The method gives 90 to 95 per cent control of the ants. Its cost is only $.23 per acre. The Agriculture Department's mass control program, on the other hand, cost about $3.50 per acre—the most expensive, the most damaging, and the least effective program of all.