THE TERRORISTS' LETTER arrived at the office of the mayor of Los Angeles on Nov. 30, 1989. A group calling itself The Breeders claimed to have secretly imported, bred, and released the Mediterranean fruit fly in Los Angeles and Orange counties. And they threatened to expand the attack into the San Joaquin Valley, a major center of California agriculture.
The "Medfly" had appeared that August in survey traps not far from Dodger Stadium, and officials were spraying in an effort to get rid of it. The pest attacks 300 different fruits, vegetables, and nuts, reducing plant tissue to a maggoty pulp that rots and falls to the ground. An established infestation would bring widespread destruction and mean that produce could no longer be shipped out of state, potentially costing 132,000 jobs and $13.4 billion in lost revenues.
Eventually the infestation ended, after heavy spraying. There is still debate about whether ecoterrorists stoked the Medfly infestation, but the panic the episode engendered suggests that The Breeders were flirting with a powerful weapon.
One of the cheapest and most destructive weapons available to terrorists today is also one of the most widely ignored: insects. These biological warfare agents are easy to sneak across borders, reproduce quickly, spread disease, and devastate crops in an indefatigable march. Our stores of grain could be ravaged by the khapra beetle, cotton and soybean fields decimated by the Egyptian cottonworm, citrus and cotton crops stripped by the false codling moth, and vegetable fields pummeled by the cabbage moth. The costs could easily escalate into the billions of dollars, and the resulting disruption of our food supply - and our sense of well-being - could be devastating. Yet the government focuses on shoe bombs and anthrax while virtually ignoring insect insurgents.
Indeed, a great strategic lesson of 9/11 has been overlooked. Terrorists need only a little ingenuity, not sophisticated weapons, to cause enormous damage. Armed only with box cutters, terrorists hijacked planes and brought down the towers of the World Trade Center. Insects are the box cutters of biological warfare - cheap, simple, and wickedly effective.
"I can write for you on a postcard a series of different ways to paralyze the agriculture industry of the United States, where we have no possibility of being able to respond," said Geoff Letchworth, the former director of the US Department of Agriculture's Arthropod-Borne Animal Diseases Research Laboratory.
Insects have always carried the potential for great human catastrophe. In the 14th century, 75 million people succumbed to a flea-borne pandemic of bubonic plague. But few people realize that the Black Death arrived in Europe after the Mongols catapulted flea-ridden corpses into the port city of Kaffa. From there, the people fled and carried bacteria, rats, and fleas throughout the Mediterranean.
And it was lice, not Western armies, that nearly broke the back of the Soviet Union when typhus sickened 30 million people and killed 5 million Russians after World War I. In 1919 Lenin pronounced, "Either socialism will defeat the louse, or the louse will defeat socialism" - and the insect nearly won.
Seeing the potential, military strategists have been keen to conscript insects during war. In World War II, the French and Germans pursued the mass production and dispersion of Colorado potato beetles to destroy enemy food supplies. The Japanese military, meanwhile, sprayed disease-carrying fleas from low-flying airplanes and dropped bombs packed with flies and a slurry of cholera bacteria. The Japanese killed at least 440,000 Chinese using plague-infected fleas and cholera-coated flies, according to a 2002 international symposium of historians.
During the Cold War, the US military planned a facility to produce 100 million yellow-fever-infected mosquitoes a month, produced an "Entomological Warfare Target Analysis" of vulnerable sites in the Soviet Union and among its allies, and tested the dispersal and biting capacity of (uninfected) mosquitoes by secretly dropping the insects over American cities.
Americans largely believed that only underdeveloped nations had to worry about insect-borne diseases until the summer of 1999, when West Nile virus arrived. A natural experiment in entomological warfare unfolded as public-health agencies scrambled to explain and then control a debilitating disease. In the next seven years, the technological might of the United States could not keep mosquitoes from carrying a disease across the nation to sicken nearly 7,000 people and kill 654 victims. Lacking a coherent, national infrastructure for pest management, local agencies wasted time, money, and supplies, spraying insecticides on harmless mosquitoes and missing windows of opportunity for effective control.
West Nile virus is only the tip of the pathogenic iceberg. We are vulnerable to yellow fever, malaria, dengue fever, and various forms of encephalitis. Add to this list diseases carried by the eight-legged relatives of insects. Tick-borne Lyme disease can be a terrible affliction, but far worse would be Crimean-Congo hemorrhagic fever, which causes massive internal bleeding and kills one-third of its victims. The virus is transmitted by various ticks with close cousins in the United States.
But given our losing battle against West Nile virus, the greatest concern is its African cousin, Rift Valley fever. Originally found in 1931, the viral disease caused abortions in pregnant livestock while young animals suffered 10 to 70 percent mortality. In 1977, a virulent strain appeared that is able to invade the human nervous system. Of 200,000 Egyptians who fell ill, some 2,000 lost their eyesight and 598 died of encephalitis. An outbreak in Kenya that killed 118 people just nine months ago makes clear that this disease is here to stay. Every region in the United States has a mosquito species capable of carrying this disease.
Nor would it be difficult to introduce Rift Valley fever, according to Charles Bailey, director of the National Center for Biodefense at George Mason University. A person with $100 worth of supplies, a set of simple instructions, and a plane ticket from an afflicted African nation to the United States could introduce the disease with virtually no chance of being caught, he said.
Americans are understandably worried about disease, and terrorists would relish the opportunity to introduce deadly pathogens. But our enemies are also keenly aware that we take our wealth as seriously as our health. The World Trade Center was chosen as an icon of the nation's economic prosperity. Yet agriculture accounts for a trillion dollars in economic activity and one in every six jobs in the United States. Barns, more so than office buildings, affirm the nation's cultural identity.
An entomological attack would not deplete America's pantries, but it could go a long way to emptying our wallets. In economic terms, the terrorist attacks on Sept. 11, 2001, resulted in direct losses of $27.2 billion. The Asian long-horned beetle, which arrived in 1996, together with the emerald ash borer, which was found in 2002, have the potential to destroy more than $700 billion worth of forests, according to the USDA.
Consider the maize borer, a native of India, Thailand, and East Africa that produces seven generations per year. If this pest arrives, the USDA predicts that it would infest cornfields from the Eastern seaboard, across the Gulf Coast, into the Pacific Northwest. With crop losses of 88 percent in other countries, hundreds of millions of dollars of crops are at risk - along with our energy independence as the United States shifts to ethanol-based fuels.
Insect carriers of plant diseases keep orchardists awake at night. A bacterial ailment called citrus variegated chlorosis is carried by a leafhopper, and the disease wiped out 50 million trees in Brazil. The vector is already in Florida; the only missing ingredient is an infusion of the pathogen. What would be the cost of such insect-borne diseases? If an outbreak decimated enough orchards to reduce sales of orange juice by 50 percent for a period of five years, the US economy would lose $9.5 billion - the approximate cost of rebuilding the towers of the World Trade Center from scratch.
Lieutenant Colonel Robert Kadlec, staff director for the US Senate Subcommittee on Bioterrorism and Public Health, has developed scenarios in which saboteurs conscript local insects to inflict $1 billion in damage to the American wine industry and to infest Pakistan's cotton crop, thereby crippling the country's economy and destabilizing a vital US ally in its efforts to combat terrorism.
"We've thought about car bombs and nuclear materials," Kadlec said. But "we haven't thought about weapons that are in the terrorists' domain and endemic to where they are living."
It could also be devastating to reverse the eradication of the boll weevil and other historic successes of pest management. For example, the reestablishment of the screw worm fly - its maggots feed on the tissues of living animals - could result in hundreds of millions in agricultural losses. According to the National Research Council, a bioterrorist could spread this pest across the United States for the cost of a bribe, a few quart jars, an airline ticket, and a rental car.
Sonny Ramaswamy, head of Kansas State University's department of entomology, is leading a study in which the accidental arrival of the soybean aphid - a yellowish insect that sucks the sap from plants and transmits viral diseases - shows what might happen with a pest released by bioterrorists. Since the insect's arrival in 2000, it has spread at a rate of a half-mile per day, infesting fields from the Dakotas to Virginia within four years.
"It wouldn't be as spectacular as the World Trade Center," said Ramaswamy, "but it would be more insidious."
Warnings that American agriculture was at risk of a terrorist attack began before 9/11. In June 2000, Jonathan Ban, a research associate at the Chemical and Biological Arms Control Institute, published an analysis that maintained that given the value of US agriculture, the federal government had been "slow to realize their vulnerability to attack."
In 2003, well after 9/11, the NRC released Countering Agricultural Bioterrorism, a scathing report of America's vulnerability that concluded that the federal effort was "insufficient for effectively deterring, preventing, detecting, responding to, and recovering from agricultural threats."
Since then, the government has moved backward, cannibalizing the USDA in order to feed resources into the Department of Homeland Security. In 2003, the White House moved 2,000 inspectors from the Animal and Plant Health Inspection Service - the branch of the USDA responsible for detecting and suppressing invasive pests - to DHS Customs and Border Protection. A Government Accountability Office report released this fall revealed that a majority of the inspectors who were assigned to DHS say their ability to protect agriculture has been compromised by low morale, training deficiencies, equipment shortages, and manpower shortfalls. Nothing gets a lower priority than agriculture in the DHS hierarchy of concern.
The US government's stacking of its defenses along the borders is an egregious strategic error. The better model is that of public health. Rather than hoping to stop every sick traveler from entering the country, we stockpile vaccines, train health professionals, and educate the public (although not nearly to the extent that would make sense). It will never be possible to thoroughly inspect more than a tiny fraction of the 1.4 million planes, ships, and vehicles that enter this country each year. The best approach to deterring and responding to an attack is to have flourishing human and agricultural health systems that can detect and quash whatever comes.
For agriculture, such a system should begin with educational programs and trained observers capable of recognizing new pests. When a novel insect is found, the nation needs specialists who can make a rapid and definitive identification: The nationwide shortage of medical entomologists, noted by the Centers for Disease Control and Prevention in the aftermath of the West Nile outbreak, must be addressed.
There should also be stockpiles of chemicals or the industrial capacity to respond rapidly to high demand. Likewise, we need the capacity to mobilize aerial applicators, who increasingly struggle to stay in business.
Finally, after the initial response the nation must have the ability to move quickly and effectively from chemical control to more sustainable practices, such as biological control with carefully selected natural enemies. These measures are consistent with the NRC's 2003 report, and have been known to specialists for years. Unfortunately, the federal government has downsized agricultural extension (the USDA's education and applied research function), underfunded diagnostic services, and otherwise failed to develop the surge capacity needed to respond.
An effective pest-management infrastructure would pay for itself. Even without help from terrorists, new pests will infiltrate our borders. In the last century, an estimated 553 nonnative organisms settled in the United States, and two-thirds were insects. The 43 insect species for which economic analyses have been conducted account for $93 billion in losses.
Americans tend to think in terms of the short-term spectacle and heroic saviors of Hollywood action movies. Our disconnection from the natural world has led us to believe that risk and benefit unfold at a blistering pace. But even prolific and mobile insects take years to spread across the country. Some take decades. The gypsy moth arrived in 1868 and is still moving westward. For a terrorist group with patience, a slow motion disaster in ecological time would be a perfect tactic against an enemy that thinks in terms of days or months but would, nonetheless, suffer across generations.
Jeffrey A. Lockwood, an entomologist, is a professor of natural sciences and humanities at the University of Wyoming. He is the author of a book about the uses of insects in war, to be published by Oxford University Press in fall 2008. he can be reached at firstname.lastname@example.org.