Yobs who smashed up hives and killed around 10,000 rare bees got a “sick pleasure out of the destruction”, devastated staff said.
Staff at Wisbech Castle on the Lincolnshire border have hit out at the vandals, who are still on the loose.
The castle’s chairman said they’ve had problems with vandals for a while but “archaic rules on heritage buildings” prevent them from taking action.
Steve Tierney said: “Being refused simple things like putting anti-climb measures on the walls is unreasonable, counterproductive and bloody-minded.
“It often seems as though the heritage rules, and the people who enforce them rigidly, are completely out of touch with the real world.”
The incident happened at about 5.15am on January 8.
CCTV showed two people breaking into the castle grounds and lifting the lids off of the hives, before kicking them and attacking the bees inside with sticks.
It will cost the museum around £2,000 to restart the project in the spring.
They estimate around 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.
“Some wall spikes, anti-climb paint, and other counter-intrusion measures would make this much easier.
“If we are worried about the damage to the ancient wall, you should see the damage that is being done by people climbing over it all the time.
“Volunteers are very angry. We won’t be resting on this,” added the chairman.
Anyone with information regarding this incident should call police on 101 quoting 35/1817/20 or visit www.cambs.police.uk/report. Alternatively, contact Crimestoppers, anonymously, on 0800 555111 or via www.crimestoppers-uk.org.