Light-fingered monkeys unable to resist the bright lights and bleeps of mobile phones have been taught not to steal.
Squirrel monkeys are native to South America
Previously, squirrel monkeys in London Zoo's new barrier-free enclosure were tempted to take visitors' phones.
But since staff covered unwanted phones in an unpleasant sticky substance, the animals were soon put off and gave up their bad habits.
"They are back to their usual pastimes of sleeping and foraging now," said Malcolm Fitzgerald from the zoo.
Visitors to the walk-through enclosure designed to replicate a Bolivian forest would hold out their camera phones to video or take photographs drawing the monkeys' attention away from their usual habits.
Mr Fitzpatrick, curator of mammals for the Zoological Society of London, said: "The new barrier free enclosure means the monkeys are in closer proximity to visitors.
"It's important that the monkeys maintain their natural behaviour and training them not to go for visitors' phones was essential to achieving this."
Squirrel monkeys are native to South America where they are under threat.
Currently London Zoo, together with other zoos in England, is involved in breeding programmes aimed at increasing numbers of the species.
They are often pets, and used for biomedical research, bait and food.