Lost nuc

[nemphlar]

Looking for advice, 5 frame nuc made with all the QC's from a large swarming hive, into their 3rd super. No signs of big varroa numbers in parent hive or nuc.
Checked nuc today lots of perfectly formed crawling bees and mesh floor covered in dead bees,tried under the microscope can't see anything obvious.
Parent hive still working. I've never seen or heard of Acarine in this area

[fatshark]

Plenty of stores? We've got nucs needing syrup whereas large colonies, with plenty of foragers, are managing to bring enough nectar in. You're well North of me, so might not be in the June gap yet.

If varroa was the issue, you'd see loads of DWV. This would be obvious.

Parent hive in the same apiary I presume otherwise I'd wonder about sprays … ?

[nemphlar]

Yes they have stores FS
Parent at back of garden with nuc at front along with 8 other mating colonies. Check 5 minutes ago and looks like they will all be dead by morning. I've taped up the box incase robbers move in

[Adam]

Stressed and overheated whilst shut up perhaps?

[nemphlar]

Possibly, in the absense of any convincing evidence I've erred on the side of caution and dropped the frames in the garden incinerator