Colony absconded - was it due to varroa?

[RichardK]

Over the last week I've had a colony abscond. I didn't think it could be varroa related until I dismantled the hive and saw the base board, picture below. With work commitments I've not managed to complete 5 oxalic acid vape treatments 4 or 5 days apart but have done a set of 4 and another 4 or 5 isolated vapes. The first 24 hours did show a reasonable drop but over time this has decreased enormously to the extend that the last isolated vape I did (16th Nov) the drop wasn't much comparatively - I didn't count but lets say 50 mites over 24 hours.

But then I saw the base board. I've not seen this before but am guessing it could show that larva were being pulled from the cells presumably due to varroa? If this is varroa, I must have still had a very heavy infestation?

 

[Parsonage Bees]

Not as many as this but saw today immature bees (white abdomens) thrown out the front.
They have a high varroa level. Last treatment was Apiguard through September. Waiting to OAD in couple of weeks.
My guess is that some brood was chilled when we had a -7degC overnight a few days ago. ?
Don't think any colonies absconded tho'. Logically, 'absconded' ? . . . where would they go? They've died out.

#edit Perpignan. Didn't realize how far south you are. You're on the Med and virtually in Spain. Don't think any of my comments above about weather apply to you.