Police have condemned a "cruel and completely unnecessary act of violence" after 10,000 rare bees were killed by intruders at Wisbech Castle.
The two people broke into the castle grounds just after 5am on 8 January.
They then lifted lids off of the hives, before kicking them and attacking the bees inside with sticks.
Staff at the castle believe as many as 10,000 bees died in the incident.
The beehives had been introduced to the castle as part of a black bee conservation project to protect the endangered species.
Officers want to speak to two people pictured on CCTV.
“This was a cruel, unprovoked and completely unnecessary act of violence and castle staff are, understandably, devastated by the incident," PC Kirsty Hulley from Cambridgeshire Police said.
“They estimate as many as 10,000 rare bees have died, but are unable to check properly until March as further exposure to the cold air would kill the remaining bees.
“It will cost the museum around £2000 to restart the project in the spring.
“I would urge anyone who recognises the people pictured, or has information concerning what happened, to contact us.”