An RSPCA inspector was called out to deal with a tarantula in a house in Hampshire, only to discover it was a child's toy.
The householder had reported seeing a spider "the size of her hand" hiding in a downstairs cupboard.
Inspector Nikki Denham was prepared with gloves and nets to trap the spider, but after shining a torch in the cupboard saw it was plastic.
The RSPCA said the woman was "obviously embarrassed".
Ms Denham said the householder in Alresford had closed all doors to prevent the spider's escape before she arrived.
"It was dark under the stairs, but I could see legs behind a vacuum cleaner that certainly were tarantula size.
"However, as I shone light in I could see that it was in fact a toy plastic tarantula," she said.
She said the toy was shown to the woman's young son who confirmed it was his - "with an angelic innocent face".
A RSPCA spokeswoman said the organisation was called on to rescue 275 genuine tarantulas in 2016.