Sue Weightman purchased the cupcakes from the Little Waitrose in Milton Street, Nottingham, for her son Alex’s birthday.
Speaking to the Nottingham Post, Weightman said: “Alex bit into it and found a wasp inside the icing. He refused to have any more food. I'm not happy. I expected standards.
“We want to know if it was malicious or whether it could have just dropped down in the atmosphere. They need to learn from this.”
In response, a Waitrose spokesperson said: “We take customer safety very seriously and are very sorry for any distress caused.
“Although this is an isolated incident, we are investigating with our branch and our suppliers how this could have happened.
“We have personally apologised to the customer and will inform her of the results of the investigation.”