Newly released government files indicate that the administration of former British Prime Minister Margaret Thatcher explored a clandestine plan to eradicate South American cocaine crops by deploying swarms of leaf-eating moths. The proposal, developed during Britain's intensive war on drugs, aimed to use insects bred by scientists at Porton Down in Wiltshire and release them via helicopter over coca plantations in Peru.
The initiative, which saw approximately £100,000 invested, centered on the moth species Eloria noyesi, whose larvae consume coca leaves—the primary ingredient for cocaine production—without apparent harm. Officials saw the moth as a potential biological weapon against powerful drug cartels operating in Peru.
Documents from 1989 detail how military scientists were tasked with investigating the feasibility of mass-breeding these moths for release over illicit plantations. This concept was reportedly inspired by a natural infestation of Eloria noyesi that destroyed around 2,000 hectares of coca cultivation near Tarapoto, Peru, between 1987 and 1988, causing significant financial losses for traffickers.
Peruvian authorities had sought British assistance in establishing a large-scale rearing program, suitable for staff with limited experience. Files show that Thatcher personally supported further research into the project, deeming it "sufficiently interesting to merit being pursued."
However, the plan eventually faced obstacles concerning its projected effectiveness and potential environmental repercussions. The Home Office reportedly concluded that while technically achievable, the impact on cocaine production would likely be short-lived. By the end of 1989, ministers also raised concerns that any public disclosure could jeopardize the operation and endanger individuals involved. Consequently, the plan to combat drug cartels with weaponized moths never advanced beyond the conceptual stage.