Mankind devotes boundless ingenuity to devising new means of killing enemies. Yet, until very recently, it has been less successful at this than has nature. Disease has accounted for far more wartime fatalities than have swords, spears, bombs or bullets. Recognising this, nations have often sought to harness disease to military ends. In the Middle Ages, it was an accepted tactic to catapult rotting and insect-riddled animal carcasses into beleaguered cities.

The problem was to ensure that only the other side suffered the consequences. Plague frequently broke out among besieged inhabitants - but so it did also among the besiegers. The Mongol khan Janibeg deployed disease-laden fleas to hasten the capture of the Genoese city of Kaffa in 1343. But it is doubtful that he could claim complete success: a European plague followed, which killed 25m people.

Jeffrey Lockwood, a professor of entomology at the University of Wyoming, seeks to explore the history of attempts to use insects for military purposes from earliest times to modern threats of bioterrorism. He sweeps into his collecting net a miscellany of myth, legend and historical fact that is seldom less than entertaining, but scarcely scholarly. He writes, for instance, about the Ark of the Covenant: “The historian Adrienne Mayor has suggested that this sacred chest might have been guarded by plague-infected fleas.” Indiana Jones's scriptwriters or Christian fundamentalists might buy into that yarn, but it seems odd for academics to do so.

There is a confusion in Lockwood's narrative between acts of God and man-made contrivances. He states that 200,000 of Napoleon's 1812 Grand Army in Russia died of typhus borne by fleas. He also writes: “The [American] civil war showcased forms of entomological warfare that military commanders had been refining for centuries.” It is true that two-thirds of the conflict's 488,000 deaths were the result of disease rather than gunshot. But this was because the rival combatants did not know any better, rather than because generals Grant and Lee were clever or fiendish enough to make it so.

His story changes gear when he describes the activities of the infamous Japanese Unit 731 in Manchuria during the second world war, vividly exposed in 2004 by Daniel Barenblatt in his book A Plague upon Humanity. General Shiro Ishii directed the efforts of 3,000 scientists at Pingfan, near Harbin. They experimented on thousands of Chinese human guinea pigs, dismissed by the Japanese as maruta (“logs”, so called because the Japanese pretended their research facility was a lumber mill). Many were subjected to vivisection without anaesthetic, and then killed off if the scientists' attentions had failed to do so.

Ishii's contribution to Japan's war in China was to bombard its civilian population from the air with plague bacilli and infection-bearing insects. Lockwood asserts baldly: “By the end of the war, Ishii's fleas and flies were responsible for more deaths than the atomic bombs dropped on Japan.”

It may sound a mere quibble, but my own research on Japanese operations in China suggested that evidence is equivocal about whether Ishii's essays in biological warfare were as successful as he claimed. Disease killed many millions of Chinese during the Japanese occupation, but it remains uncertain that Unit 731's efforts were responsible.

This does not, of course, change the moral issue. Ishii's campaign, with the full support of the Japanese government and army, represents one of the darkest stains on his country's wartime record. In 1945, when Japan surrendered, the general completed his monstrous labours by slaughtering all his remaining Chinese prisoners, and releasing a menagerie of plague-carrying rats into the local countryside. But when the Americans captured Ishii at the end of the war, and disgracefully allowed him to trade the secrets of his researches for his freedom, they found the material worthless. It was more difficult to conduct effective biological warfare than some doomsters professed.

In February 1952, at the height of the Korean war, China and North Korea launched a propaganda offensive to support a claim that the United States was dropping plague-bearing insects on their people. A so-called international commission, of scientists sympathetic to the communist cause, was mobilised by Beijing to investigate, and endorsed its allegations. Lockwood writes: “The Americans passionately denied the charges, as they did when accused of using insects to spread disease in Cuba and Vietnam. But governments often disown politically problematic knowledge.” The Russians weighed into the controversy, pointing out that America was the only UN Security Council member that had not signed the Geneva Protocol prohibiting biological warfare. It was indisputable that America possessed a huge biological warfare facility at Fort Detrick, much larger than Britain's Porton Down. The British in 1942 had made the Hebridean island of Gruinard uninhabitable for decades, by conducting an anthrax experiment there.

America and its allies, therefore, certainly possessed means to launch biological warfare. The question was: did they also possess the will? Lockwood writes: “The certainty of Americans as to their country's innocence...has diminished with the passage of time.” While he does not positively state that the USA was guilty as charged, he seems to believe that a nation capable of defoliating Vietnam with Agent Orange - and incidentally promoting widespread disease among local civilians - might be capable of anything.

There remains no definitive evidence about the Korean allegations one way or the other. I am a sceptic, on circumstantial grounds. The USA rejected the use of gas against the Japanese in the second world war for ethical reasons. While atomic bombs were dropped on Hiroshima and Nagasaki, the moral cost was so high that President Truman staunchly rejected appeals from General MacArthur and other hawks to unleash nuclear weapons against China in 1951.

China and North Korea were ruled by regimes in which mendacity was systemic. Most convincing of all, to some of us: if America had indeed waged biological war during 1951-52, hundreds if not thousands of its scientists and servicemen would have been complicit. I find it impossible to believe that some would not by now have revealed their roles, if the charges were true. It is hard to take seriously 1952 “confessions” extracted from American aircrew in Chinese captivity.

The last section of Lockwood's book is the most plausible and interesting, because it addresses the risks of biological terrorism in our own times. In particular, the author speculates about the consequences if terrorists were to broadcast Aedes aegypti, the mosquito that carries the yellow fever virus. The consequences of a yellow fever epidemic in America, where scarcely anyone is inoculated against the disease, could be devastating. The American government certainly thinks so. “Biodefence is the hottest ticket in federal funding,” writes Lockwood. Spending has risen from $250m a year in 2001 to $4 billion today. “Farms and ranches across the industrialised world are easy marks for the wannabe terrorist.” The author presumably possesses the specialist knowledge to know what he is talking about.

Yet as history, his work seems unsatisfactory. I am amazed by the willingness of Oxford, a university publisher, to lend its imprimatur to a book devoid of rigour, and notably carelessly written. A chapter heading such as All's Lousy on the Eastern Front is scarcely an incentive to take its content seriously. There is an important book to be written about biological warfare, but this one is simply a romp.

Six-Legged Soldiers by Jeffrey A Lockwood
OUP £14.99 pp400

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