Science Gone Wrong · Biology

The 23 Cats the RAF Parachuted Into Borneo to Fight a Rat Plague

On 13 March 1960, a Royal Air Force transport plane lumbered over the highlands of Borneo and pushed seven thousand pounds of cargo out the back. Down came vegetable seeds. Down came a road roller. Down came four cartons of stout for a recovering village chief. And down came twenty-odd cats, packed in wicker baskets, swinging under parachutes toward a village overrun by rats.

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The 23 Cats the RAF Parachuted Into Borneo to Fight a Rat Plague

What happened?

The story starts, as these stories often do, with a genuinely good idea.

In 1955 the World Health Assembly committed the world to eradicating malaria — a disease that was killing people across the tropics on a scale that is hard to hold in your head. The chosen weapon was DDT (dichlorodiphenyltrichloroethane), an insecticide cheap enough to use at continental scale. The method was elegant: spray the inside walls of houses. A mosquito that bites someone at night has to rest on a wall afterward, and if that wall is coated in dried DDT, the mosquito dies before it can pass the parasite along.

In Sarawak — then a British colony, now a Malaysian state on the island of Borneo — a WHO entomologist named F. de S. LaChance ran the spraying campaign, working through the interior longhouses of the Kelabit Highlands. Longhouses are exactly what they sound like: single timber buildings, sometimes housing dozens of families, roofed in thatch. The teams sprayed the walls and under the beds. The residue dried to a white powder that stayed lethal to insects for about six months.

The malaria numbers went down. Then the roofs started falling in.

At a local malaria conference, Kelabit residents reported that the thatch on their longhouses was disintegrating. Investigators found the cause living in the roof: a population of moth caterpillars that ate thatch for a living, and that had roughly increased by half. The caterpillars themselves were relatively untouched by the spraying, because they lived in the roof rather than crawling across treated walls. But a small parasitic wasp that laid its eggs inside those caterpillars — and normally kept their numbers down — was not so lucky. Remove the wasp, and the caterpillars eat the house.

Meanwhile, the village cats began dying. Reports of cat die-offs followed DDT campaigns in several countries; the usual explanation is that cats brushed against treated walls, then groomed the powder off their own fur and swallowed it. (You will often read that the cats were poisoned by biomagnification — eating lizards that had eaten poisoned insects, concentrating the chemical up the food chain. That version is plausible and widely repeated, but it has never actually been confirmed. Direct contact is the simpler explanation.)

With the cats gone, the rats arrived. A 1959 WHO field report noted that field rats were “a greater menace than usual,” partly because anti-malarial spraying had killed so many cats. In Bario, the rats went after the rice stores. According to Alastair Morrison’s memoir of colonial Sarawak, the district officer, Malcolm MacSporran, woke one night to find a rat chewing through his pillow to harvest the stuffing for a nest.

So Kuching — Sarawak’s capital, whose name happens to mean “cat” in Malay — was asked for cats. A notice ran in The Straits Times on 9 March 1960: “WANTED: 30 flying cats to rout rats.” Twenty-three were collected and packed into wicker baskets.

The RAF’s own Operations Record Book for the flight is dry and wonderful. Flying Officer Nimmo and crew flew a Blackburn Beverley out of Changi, Singapore, on a “unique drop to Bario.” The manifest lists vegetable seeds, an 800-pound vibrating roller, four cartons of stout for a recuperating chieftain, and “over 20 cats to wage war on rats which were threatening crops.” Afterward, a message came back from Bario: “Many thanks to RAF and all responsible for air drop arrangements; also to cat donors and cat basket-makers. All cats safe and much appreciated.” One parachute failed — the one carrying the wheels.

Why was it strange?

Because nobody did anything wrong, and it went wrong anyway.

Spraying the inside of a house to stop malaria is not reckless. It is targeted, low-dose, and it worked. But an ecosystem is not a list of species; it is a web of who-eats-whom, and pulling one thread moves all of them. The chain here ran: kill mosquitoes → also kill parasitic wasps → caterpillars boom → roofs collapse. And in parallel: kill insects on walls → poison the cats that touch those walls → rats boom → rice stores vanish.

The other strange thing is what happened to the story afterward. Over the decades the 23 cats multiplied in the retelling into 14,000 cats — a figure that appears in books, blog posts and viral videos and is supported by no contemporary record. Ecological cascades are real. So, apparently, are narrative ones.

What did scientists learn?

The biological lesson is about trophic cascades — knock-on effects that travel up or down a food chain when one link is removed. Bario is now a textbook case, precisely because the chain is short enough to follow with the naked eye. You can watch the roof fall in.

The second lesson is about how to argue with a good story. Patrick O’Shaughnessy’s 2008 review in the American Journal of Public Health went back through the primary material and found the skeleton true — the spraying, the cat deaths, the airdrop — but several beloved details unverified, and the whole affair enlisted by both sides of the modern DDT debate as a knockdown argument. “This really happened” and “this means what you think it means” are separate claims.

How does it affect us today?

Malaria control still uses indoor residual spraying, but with a rotating menu of insecticides chosen partly to limit collateral damage and resistance. More broadly, the cat drop became a founding parable of systems thinking in public health — the habit of asking, before an intervention, what else is connected to this?

DDT itself is now restricted worldwide under the 2001 Stockholm Convention, with a carve-out that still permits its use for disease-vector control where nothing better is available. That exception exists because the tradeoff is genuinely hard: malaria kills hundreds of thousands of people a year, most of them children.

Fun fact

The RAF record lists the cats in the same breath as “four cartons of stout for a recuperating chieftain.” Somewhere in a British military archive, in tidy official handwriting, beer and cats share a cargo manifest.

Malaria remains a serious illness. If you’re travelling to an area where it’s endemic, current prevention guidance is available from the World Health Organization and from national travel-health services.

Sources

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