Recently Catherine from Welwyn wrote to Peter Folge:
I hope all is well with you. I have had a disaster in my large colony of bees and they have all died. On 1st Sept I went to give the 3rd thymol treatment and thought the bees looked a bit lethargic - it was a cloudy day. [They were a very active big colony and had lots of brood. I have thought for sometime that they were over crowded and had given them an extra super and I knew they were a bit short of food stores.] I decided I wouldn't give the 4th treatment but would begin feeding. On 5th September I went to feed only to find 80% bees were dead I removed the thymol, fed them, tipped out the dead bees - thousands. I hoped the remaining 20% would survive but no all are dead. There are dead emerging larvae & I think the brood is dead. The other hive is OK but has no brood, some has recently hatched. I think what has happened is that they were overcrowded the weather was bad and they were short of food so a lot bees remained in the hive some probably died falling to the floor and obstructing the air flow through the varroa floor . The entrance had the mouse guard in. I suspect this allowed the thymol fumes to build up to levels which became toxic to bees resulting in more drowsy bees on the floor compounding the problem. Lots of lessons learnt and a sad story. Could be referred to as colony collapse but I think there is an explanation. I shall be much more careful with thymol treaments in future perhaps feeding before treating? I hope the others survive the winter and we can build up again next spring.
Peter wrote back:
Sorry to hear about your loss. I have had 3 nucs abscond this year but I did overdose all colonies with thymol crystals. The nucs were on solid floors not open mesh and one was placed in a full hive body with a queen excluder between floor and brood chamber. When I came to inspect all bees were gone and queen was left behind and died.
Open mesh seems not to have a problem. Absconding occurred every time there was no food left for the bees.
In your case it looks like the bees starved! This happened to an artificial nuc I made up last year and I knew needed feeding. I left it one week to find most were already dead. Overcrowding is not a problem at this time of year as bees should not swarm and numbers dwindle down fairly quickly. A large colony without any food reserves will die in a couple of days and still needs adequate ventilation.
We unfortunately continuously have to learn and adapt our methods even if it means doing things the hard way.
Just make sure you feed your other hive 2-3 gals (9-14 litres). This should get them through winter. Since July there has been little to find and the bees have been consuming stores.
All the best wishes.