Fourteen beehives and thousands of bees have been stolen.
North Wales Police believe they were probably taken at night by someone with knowledge of beekeeping from Mynydd y Garth, near Llangollen, Denbighshire.
The number of bees taken has not been disclosed, but officers are appealing for information about anyone with a “sudden influx” of hives, or who is selling them or colonies.
One experienced beekeeper said it would be a “terrible blow” for the owner.
The theft took place between Monday and Wednesday, and police said the owner had lost thousands of pounds worth of bees and honey.
Police Community Support Officer CSO Iwan Owen said whoever took them from Blackwood Lane last weekend came prepared.
“A total of 14 hives have gone, so they’re likely to have been taken in a vehicle similar to a long wheelbase Ford Transit, or a trailer,” he said.
“They are likely to have been taken late at night because the bees would presumably return to the hive after about 8.30pm.”
Hobby beekeeper Cathy Williams, who lives near Wrexham, has been beekeeping for about 10 years, a hobby that has been in her family for generations.
She has eight hives which produce about 226kg (500lbs) of honey a year and is a member of the South Clwyd Beekeepers Association.
“My smallest one [hive], with a very small colony, we’ve only got around 2,500 bees, but a really good strong colony will have anything upwards of 60,000,” she said.
‘Very serious’
“It would be catastrophic. If it was a bee farmer – it was 14 hives that were stolen – that would make a big punch in his profits for the year, a huge punch and it would set him right back to next year.
“It’s because the colony goes on from year to year, season to season through its lifecycle and if you’ve lost all those bees, you’re not going to have honey from those colonies next year, it’s really very serious.
“If they are hobby beekeepers like me then you have lost everything. It’s a terrible blow.”
She agreed with police that the culprit would need knowledge of bees.
She said that at this time of year bees were making “lots and lots of honey” and building up their numbers for the winter.
“So the colonies now are pretty big, on the whole, so whoever has taken these has got very probably very good sturdy colonies, which will then go through the winter.
“If they were to steal spring colonies, they will probably be a lot smaller.
“So again, whoever has stolen them knows what they’re doing.
“They know that these that these colonies are big and desirable for people who perhaps don’t know a lot about them, but want to have them.
“We would normally think of getting new colonies in the spring, we wouldn’t think of necessarily buying colonies at this time of the year.”