The Big Itch

Better dead than Red. The western mantra of the 1950s. And people meant it. With this sort of sociopolitical view, it is little wonder that the U.S. military pursued every conceivable means of defeating the soulless communists—even conscripting insects as unwitting patriots. After all, if entomological weapons based on bungled Japanese science had killed nearly half a million people, just think what an advanced nation might be able to do with these creatures. Or imagine what a technologically sophisticated foe might accomplish.

With the Soviet Union detonating an atomic bomb in 1949, Cold War anxiety paved the way for a series of incredible experiments in the name of protecting democracy. The official rationale for these studies was to prepare a civil defense plan, but of course any data concerning how the American populace might be put at risk by biological warfare were eagerly converted into the development of tactics for attacking the Soviets and their allies.

Field studies of biological warfare most infamously involved the secret releases of "simulants" to mimic clandestine attacks with deadly microbes.1 In collaboration with the CIA, Camp Detrick scientists began by dispersing theoretically harmless and easily traced bacteria in the Pentagon's ventilation system, then moved on to contaminating subway systems and office buildings. Still larger targets were fogged with zinc cadmium sulfide, a florescent compound that could be formulated to drift like airborne bacteria. In 1950, whole cities were sprayed from naval ships, with 800,000 clueless people inhaling some 4 billion particles in the course of an experiment off the coast of San Francisco. Over the next few years, clouds of bacterial simulants and chemical markers were released in more than 200 unsuspecting communities across the country. There were no reports of serious infections or adverse reactions among the citizenry, but the military had little incentive to go looking for problems (see Figure 17.1).

Figure 17.1. Camp Detrick's "Black Maria" (ca. 1945) was a wooden building covered in tar paper; it served as the shell housing the nation's first laboratory for offensive research on biological weapons. The smokestack was part of the boiler system used for incinerating experimental animals. Within the compound, each scientist was armed with a .45 caliber pistol. A soldier in the guard tower stood ready with a Thompson submachine gun. (Courtesy of the Department of the Army)

Figure 17.1. Camp Detrick's "Black Maria" (ca. 1945) was a wooden building covered in tar paper; it served as the shell housing the nation's first laboratory for offensive research on biological weapons. The smokestack was part of the boiler system used for incinerating experimental animals. Within the compound, each scientist was armed with a .45 caliber pistol. A soldier in the guard tower stood ready with a Thompson submachine gun. (Courtesy of the Department of the Army)

Despite reams of data from experiments on the American public and a doubling of the research program at Camp Detrick, the future of germ warfare did not look promising.2 Technological sophistication had been the driving principle behind aerosol delivery. The bacteriologists' dream was to isolate pathogens, which could be cultured in staggering quantities, and directly infect the enemy. While insect-borne diseases were some of the best candidates for wea-ponization, the vectors were difficult to produce, handle, store, and disperse. However, the American scientists ran into the same problems that vexed the early work of Unit 731: pathogens are immobile wimps. So the microbiologists reluctantly but ineluctably turned to the entomologists to provide the means for delivering the virulent but vulnerable pathogens.

The researchers soon began to see the advantages of using insects as miniature missiles for delivering pathogenic warheads. While microbes are aerial plankton, biting insects are consummate hunters, able to track their victims using an unparalleled sense of smell. As an added bonus, while gas masks excluded airborne germs, insects could circumvent this defense by squirming beneath clothing or finding patches of exposed skin. Moreover, the vectors could survive for days in the environment, their hunger mounting until an unwary enemy removed their protective gear or moved into the area.

The U.S. military used a bit of discretion when it began field-testing entomological weapons. Named with a touch of gallows humor, Operation Big Itch took place on the bleak landscape of Dugway Proving Grounds.3 The goal was to determine if fleas could be reared, transported, loaded into munitions, and then delivered to a target in sufficient numbers to transmit disease to an enemy. The insects were not infected with plague, but the ultimate endpoint of this venture was to improve upon the success of the Japanese.

So it was that in 1954, from the skies over the Utah desert, fleas rained down on cages of guinea pigs. The most uncertain aspect of the operation was whether the vectors would survive and disperse after being launched from rather novel devices. The E-14 and E-23 munitions worked along similar lines: a cardboard cylinder about the size of a container of oatmeal was equipped with a mechanism to expel a burst of carbon dioxide from a pressurized cartridge. The force of the gas would rupture a bag of fleas within the cylinder, expelling them like shotgun pellets as the device tumbled earthward from a height of 1,000 to 2,000 feet.

Except for a couple of glitches, Operation Big Itch was a success. Very few of the fleas died during transport, the munitions worked brilliantly, the insects descended without incident, and the guinea pigs became infested. The only biological drawback was that the fleas gave up on finding hosts within 24 hours, so it was evident that this entomological weapon would need to be used in close proximity to the enemy—at least if we were waging war on furry rodents in a desert. The other operational drawback was fixable but a bit more worrisome.

In one of the trials, the E-23 components "malfunctioned," a euphemism for what might have been a disaster if the fleas had been carrying plague.4 The munition was supposed to become armed when a strip of sealing tape was removed, but one of the devices discharged while still in the plane. The hungry insects demonstrated their host-seeking capacities, biting the pilot, bombardier, and a military observer. But the Americans had an even bigger problem than insubordinate fleas.

While the entomologists were planning a facility to produce 50 million fleas per week, the microbiologists were struggling to mass-produce plague bacteria. During the Cold War, the Soviets managed to culture and weapon-ize Y. pestis, but U.S. researchers never cracked the problem. So, the military turned its attention to another insect-borne disease with perhaps even greater potential.

The golden child of the American entomological warfare program was the yellow fever mosquito, Aedes aegypti. With the medical community pursuing the eradication of this insect from the United States, the possibility of mass-producing the vector put military interests squarely at odds with public health ideals. This was a battle that the generals would not lose. The real challenge would be finding a way to produce enormous quantities of infected mosquitoes. Feeding millions of the adult insects on sick animals seemed to be impossibly complicated. Although this was the natural means of infection, the scientists at Camp Detrick were not constrained by such limitations.

The breakthrough came when researchers attempted a seemingly absurd experiment, adding the virus to the watery medium in which mosquito larvae squirmed and fed.5 No such route of infection was possible in nature, so nobody held much hope that the wrigglers would uptake the pathogen from their aquatic surroundings. But when adult mosquitoes emerged a few days later, they were fed on mice that—to the sheer delight of the scientists— contracted yellow fever. With the newfound capacity to efficiently mass-produce infected mosquitoes, the next step was to determine if the insects could be weaponized. And this meant testing the vectors in the real world.

Operation Big Buzz was a simulated, mosquito-based attack.6 More than a million uninfected Aedes mosquitoes were reared and stored for two weeks to simulate operational conditions. In May 1955, about a third of the insects (the others were used in loading and storage tests) were packed into E-14 munitions and dropped on rural Georgia because the southern United States was a hospitable environment for mosquitoes. Human volunteers (and guinea pigs) were placed at regular intervals from the target. Aedes aegypti spread into the countryside and managed to find hosts nearly a half-mile downwind from the release site. The first field test of vectors against human targets had been a rip-roaring success.

Although fragments of declassified military records reveal the workings of Operation Big Buzz, only the general nature of the next two projects can be inferred. Both Operation Drop Kick and Operation Grid Iron likely involved releases of mosquitoes, but the details of the experiments are not publicly available.7 The shift to a football theme in the naming of these operations is curious, but perhaps the military did not want to provide the enemy with clues as to the essence of the projects. Or perhaps cute names no longer had a place in what was becoming a deadly serious military program. For the United States had new reasons to worry about a biological Armageddon.

In 1956, Soviet Defense Minister Georgy Zhukov announced that biological and chemical warfare would be used by their armed forces in future wars.8 In response, the United States frantically reassessed the nation's vulnerability to these weapons—and the military's capacity to retaliate in kind. If the policy of "Mutually Assured Destruction" was viable for nuclear arms, then extending this strategy to other weapons of mass destruction seemed logically consistent, although it is difficult for any government to be rational when planning to kill millions of people.

The United States had long maintained strategic ambiguity regarding biological warfare, but the communist threat provided the perfect opportunity to make explicit the American policy. The National Security Council bluntly expressed the country's willingness to retaliate in kind:

To the extent that the military effectiveness of the armed forces will be enhanced by their use, the United States will be prepared to use chemical and bacteriological weapons in general war. The decision as to their use will be made by the President.9

As for the matter of international law, the army's position was that "the United States is not party to any treaty now in force that prohibits or restricts the use [in] warfare of toxic or nontoxic gases, of smoke or incendiary materials or of bacteriological warfare."10 With the moral and political obstacles out of the way, the development of biological weapons was limited only by science's capacity to conscript and coerce living organisms.

By this time, the scientists at Camp Detrick had a growing inventory of arthropod vectors available for further testing in terms of defense—and continued development with respect to offense. There were colonies of mosquitoes infected with yellow fever, malaria, and dengue; flies harboring dysentery, cholera, and anthrax; fleas carrying plague; and ticks loaded with tularemia, relapsing fever, and Colorado fever. The thriving entomological warfare division was attracting a cadre of outstanding researchers, drawn by the military's advertisements that sidestepped the ultimate goal of the research while promising an unparalleled opportunity to carry out "basic studies of effects of rearing procedures for various insects on longevity and fecundity [and] the effects of different environmental factors on infection of insects and on virulence of microorganisms."11 But with the heightened international tensions, the scientists were expected to focus on more pragmatic goals. Like killing the enemy.

After investigating other insect-borne diseases, the U.S. Army Medical Command concluded that the yellow fever virus was the best pathogen to use against—and the most likely agent to be used by—the communists.12 Military analysts had coldly calculated that virus-infected mosquitoes were more cost-effective than germ-laden aerosols if the goal of an attack was to maximize mortality (a bacterial fog was more economical in terms of generating casualties). The southern states were viewed as a prime target—the backwater of the nation, with poor medical services and crude pest-management practices. DDT was a viable defense, but only if an afflicted region had modern equipment to apply the insecticide. Nor were these analyses merely mental exercises. The seriousness with which the U.S. military took the Soviet threat was exemplified in the elevated status granted to Camp Detrick, which became Fort Detrick in February 1956 (see Figure 17.2). Along with this came a new round of secret studies of mosquitoes—and the human test subjects were no longer volunteers.

From April to November 1956, within residential areas of Savannah, Georgia, the U.S. military conducted simulated attacks using uninfected mosquitoes. Although many of the details are lacking, the first experiment—

Figure 17.2. Camp Detrick's infamous Building 470 was built in 1952 as a pilot plant for the production of pathogens for use in biological weapons. The seven-story facility contained large tanks for culturing anthrax. Decontaminating the building proved extremely difficult and costly, so it sat for years as a symbol of the dangers lurking within. Not until 1988 was it finally turned over to the National Cancer Institute for renovation. (Courtesy of the Department of the Army)

Figure 17.2. Camp Detrick's infamous Building 470 was built in 1952 as a pilot plant for the production of pathogens for use in biological weapons. The seven-story facility contained large tanks for culturing anthrax. Decontaminating the building proved extremely difficult and costly, so it sat for years as a symbol of the dangers lurking within. Not until 1988 was it finally turned over to the National Cancer Institute for renovation. (Courtesy of the Department of the Army)

code-named Operation May Day—was intended to determine whether mosquitoes released as if they'd dispersed from bombs and warheads (the Sergeant missile was being considered as a potential delivery system) would find and bite people.13 The insects reliably fed on the unsuspecting public, and these encouraging results provided the foundation for the next study.

In the Avon Park Experiment, 200,000 mosquitoes were released from aircraft over a Florida bombing range.14 The dispersion system is not specified in the available records, but the army likely used its new XM28, a "bagged-agent dispenser" with a 700-pound payload consisting of 2,090 paper bags loaded with hungry insects. Although the target was likewise unnamed, it apparently extended into the communities surrounding the bombing range. The inclusion of the public as nonconsenting experimental subjects can be inferred from Chemical Corps report: "Within a day, the mosquitoes had spread a distance of between one and two miles, and bitten many people."15 We know even less about Operation Quickhenry, except that whatever was done must have worked extraordinarily well. For in the late 1950s, the U.S. military undertook a remarkable series of experiments that culminated in a chilling analysis of the potential of entomological warfare.

The Bellwether tests were the most extensive experiments on the use of mosquitoes as weapons, and many of the relevant details can be gleaned from declassified records.16 Bellwether One consisted of 52 field experiments in the fall of 1959. The research was designed to assess the role of environmental factors on the capacity of mosquitoes to find and feed on hosts. Wind speed was found to be crucial in determining whether the vectors could locate a host, although temperature, solar radiation, and relative humidity also mattered. A typical scenario consisted of seating human volunteers around the perimeter of a 30-foot-diameter circle, with hungry mosquitoes released from the center point. Under presumably optimal conditions, for every 100 mosquitoes released, 40 blood meals were taken—a very acceptable return on investment. These small-scale investigations were encouraging, but in the course of an actual attack, the enemy would not be in such close proximity to the release point. The next step was to create more realistic conditions to challenge the mosquitoes.

In Bellwether Two, the mosquitoes had to find their human targets under a wide range of possible scenarios. Using a series of 14 tests, the researchers discovered that the frequency of biting was nearly constant out to 100 feet from the release point, but began to drop off at about 200 feet. In other words, a single release would effectively saturate an area equivalent to three football fields with bloodthirsty insects. The detailed analyses provided a vivid picture of what made for an ideal target. The mosquitoes were particularly attuned to irregular motion; people who alternately moved and rested had significantly more bites than those who continuously walked or sat. Somewhat surprisingly, individuals near buildings were bitten more often than people in open areas. Such results could not have been better in terms of an urban target, in which people typically engage in sporadic movements while surrounded by buildings.

Although there is no declassified information concerning the nature of Bellwether Three, the next experiment left no doubt that the U.S. military was developing an offensive capability. Bellwether Four was explicitly designed to determine the biting activity of mosquito strains being produced at Fort Detrick. This was the tryout to see which player would make it to the major leagues of biological warfare. Unfortunately, the competition between the Detrick and Rockefeller strains of A. aegypti was inconclusive because the researchers flubbed the experiment.

The study was intended to simulate an urban attack, with volunteers playing the role of targets for the invading insects. The problem came when the people were told that they could swat the mosquitoes, which meant that the scientists couldn't figure out whether a strain was uniformly aggressive or it had a few persistent individuals. There was, of course, the classic conclusion drawn from a badly implemented experiment—funding should be provided for further studies to resolve the issue. But even without knowing which strain constituted the optimal weapon, the military had gathered enough evidence from the Bellwether tests to decide the place of entomological weapons in the U.S. arsenal.

In 1960, the U.S. Army Chemical Corps underwent a subtle but profound shift in policy, reflecting the acceptance of entomological warfare. The military was no longer asking if insect vectors could be used against the enemy but how they could be most effectively deployed. The Corps produced an "Entomological Warfare Target Analysis," the purpose of which was to identify the qualities of susceptible targets.17 Much of the report has been excised for security reasons, but what remains paints a chilling picture. Although there were estimated to be 75 arthropod-borne diseases with military potential, the study concentrated on a subset of 18—with the Americans' golden child analyzed in grim detail.

In terms of yellow fever, a viable urban target needed to have mosquitoes penetrate just 3 to 5 percent of the houses and buildings. Because A. aegypti typically feeds on humans while they are indoors, the exposure of a population to the vector declines with the use of air conditioning and the consequent closing of windows. But the study revealed that if even a small portion of a city's structures were accessible to mosquitoes, the disease could gain a foothold. With respect to ecological conditions, if ambient temperatures were between 61 and ioi°F, the insects could readily find their hosts. Once a locus of infection was established, female mosquitoes had only to feed on a diseased host within three days of the onset of symptoms and the insect would become a carrier for life. This multiplier effect would create an escalating cycle of infection and transmission, leading to a full-blown epidemic within weeks. The primary limitation would be the immunological condition of the target population; if people had previously survived yellow fever, they would not become reinfected.

Much to the delight of the American military planners, the Soviet Union was loaded with susceptible targets—cities within the proper temperature range and packed with bodies that had never been wracked with yellow fever. Even better, some prospective targets already had A. aegypti, so it would be nearly impossible to detect the added mosquitoes or to trace their source. Although the Soviets had a yellow fever vaccine, in the judgment of the analysts it "would be impossible for a nation such as the USSR to quickly undertake a mass-immunization program to protect millions of people."18 The American planners were clearly thinking of initiating an epidemic of enormous proportions. Potential targets can be inferred from the third appendix of the report, including Moscow, Stalingrad, and Vladivostok, along with the Soviet-allied cities of Basra and Cairo. The Chinese urban centers of Canton, Shanghai, and Tsingtao also made the list. But spreading millions of infected mosquitoes over communist metropolises would require not only a sophisticated delivery system and finely honed logistics but also an incredible stockpile of insects.

By 1960, the entomologists at Fort Detrick could produce half a million infected mosquitoes per month. As impressive as this was, it fell far short of the number of insects needed to attack a major city. So the military drafted plans to increase production by nearly a thousandfold.19 Pine Bluff, a small cotton-producing town in southeast Arkansas, would house the largest insect-rearing facility in the world, a mosquito mill with the capacity to produce 100 million infected vectors per week. While some historians put the production figure at a more modest 130 million mosquitoes per month, even this figures leaves no doubt that the Americans considered entomological warfare to be a deadly serious enterprise.

Producing enormous quantities of living organisms had been the forte of Pine Bluff Arsenal for a decade. In the fall of 1950, the U.S. Congress secretly appropriated $90 million to renovate the aging installation. The new plant boasted a ten-story building that housed enormous fermentation tanks for the production of pathogenic organisms. When the military decided that brucellosis would make a keen weapon in 1953, the plant cranked enough bacteria to fill more than 2 million bombs a month.20 Just two years later, Pine Bluff took on the large-scale production of tularemia bacteria. When the order came to rear insects, the arsenal had plenty of "can do" experience.

With an annual operating budget of more than $5 million and nearly 2,000 workers swarming over a site that had grown to cover more than two square miles, there would be no problem retooling the factory. If the military wanted to grow mosquitoes, then a few 45,000-gallon stainless steel vats would be the ticket.21 But just as the Pine Bluff Arsenal was cranking up to mass-produce insects, the microbiologists were preparing to pull the rug out from under entomological warfare.

The 1960s saw scientists begin making rapid progress in the safe, large-scale production of pathogenic microbes.22 They were mastering techniques for purifying and stabilizing formulations of bacteria, viruses, and rickettsiae. Weaponization was just around the corner, with the engineers developing munitions that would release aerosols of optimally sized particles. In these heady days of biological warfare, the operational problems of microbial aerosols were profoundly underestimated. Today's experts realize the difficulty of formulating a pathogen so that it both stays airborne long enough to be inhaled and survives desiccation and ultraviolet radiation while aloft. We now appreciate that even with such a weapon, the aerosol must be released at a time and place in which wind speed and direction ensure effective dispersal.

Logistical challenges notwithstanding, advances in germ warfare meant that insect vectors began to fall out of favor. A political superpower should base its biological warfare program on stainless steel vats and sophisticated spray apparatus, not pools of squirming larvae and Rube Goldbergesque dispensers of insect-filled paper bags. The insects represented everything that a high-tech army found undesirable: a swarm of mosquitoes was disobedient, inefficient, and unreliable. Insects might have been entirely drummed out of the service had not geopolitics interfered with the microbiological hegemony.

The Cold War was heating up in an area of the world in which insects called the shots: the steamy tropics of Southeast Asia. In August 1964, the Gulf of Tonkin Resolution converted a clandestine conflict into an open war. In Vietnam, the American military was about to learn some very difficult lessons about guerrilla tactics—and entomological weapons.

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