A biome at the Eden Project is being overpopulated by ants.
The problem is confined to one of the biomes
The problem was highlighted by a visitor who complained that there was a "plague" of the insects.
The centre has decided to reduce the humidity inside the humid tropics biome in the hope of reducing an estimated population of 15m ants.
A spokesman for the centre said a large population of ants was to be expected in a contained rainforest but numbers needed to be kept in check.
Visitor Paul Pocock complained to the centre after seeing ants crawling on hand rails, seats and all over the ground.
"The ants were coming from everywhere. Wherever you were sitting there were ants.
"To say there is a plague is not far off.
"I contacted Eden and they apologised."
The centre is to try to cut down the population by lowering the humidity in the biome by 2% and managing other life forms that the ants feed off.
A spokesman said: "As you would expect with a contained rainforest, there an eco-system there. There's a large population of ants.
"A lot of people like to see insects, bugs or frogs. But we do need to keep them under control."
He said the problem was confined to one biome.