Margaret Thatcher backed secret plan to wipe out cocaine crops by unleashing swarms of leaf-eating moths over drug cartel plantations

By SOPHIA STANFORD, NEWS REPORTER Published: 00:18, 10 August 2026 | Updated: 00:26, 10 August 2026 Margaret Thatcher backed an extraordinary secret plan to wipe out South America's cocaine crops by unleashing swarms of leaf-eating moths over drug cartel plantations, newly released files reveal. The scheme, developed during the height of Britain's war on drugs, would have seen thousands of insects bred by scientists at Porton Down in Wiltshire and air-dropped from helicopters over coca fields in Peru. Government papers released by the National Archives show Thatcher's administration spent around £100,000 exploring the idea in a bid to curb the flow of the Class A drug reaching Britain. At the centre of the plan was Eloria noyesi, a species of moth whose larvae feed almost exclusively on coca leaves, the raw ingredient used to produce cocaine. Unlike most insects, the moth can consume coca leaves safely and process the chemicals without suffering any ill effects. Officials believed the insect could provide a cheap and effective biological weapon against powerful drug trafficking organisations operating across Peru. Documents from 1989 show military scientists were tasked with investigating ways to breed the moths in huge numbers before releasing them over illicit plantations. According to Foreign Office briefings, the proposal was inspired by a naturally occurring infestation that devastated coca crops near the Peruvian city of Tarapoto between 1987 and 1988. Margaret Thatcher backed a secret plan to wipe out South America's cocaine crops by unleashing swarms of leaf-eating moths over drug cartel plantations, newly-released files reveal A DEA agent stands with a blindfolded prisoner following the agency's raid on a cocaine lab in the Peruvian jungle An anti-narcotics policeman lifts a bag of cocaine captured during an anti-drug operation in connection with the Cali drug cartel in Lima, Peru on August 27, 1993 Officials noted that 'unprecedented swarms' of the moth had destroyed around 2,000 hectares of illegal coca cultivation, causing estimated losses of more than $37million for traffickers. The success prompted Peruvian authorities to seek British expertise in developing a mass-rearing programme that could be operated by relatively inexperienced staff. The files show Thatcher personally supported further investigation of the project and considered the idea 'sufficiently interesting to merit being pursued'. However, concerns soon emerged over its effectiveness and the possible environmental consequences. The Home Office reportedly concluded that while the scheme appeared technically feasible, any impact on cocaine production would only be temporary. By the end of 1989, ministers feared that any leak could jeopardise the operation and potentially endanger those involved. As a result, the brazen plan to fight drug cartels with weaponised moths never progressed beyond the drawing board.