Marty had said that the colony died before the first cold snap, so I'd been assuming that mites were the problem. Breaking down the hive, this is what we found.
- Was too much honey harvested? Honey was plentiful with at least 2 "frames" of pollen.
- Cappings on the brood combs looked normal, so I ruled out AFB. There was no discernible "brood nest" but I believe the spotty pattern is a result of good housekeeping.
- DWV. I didn't see deformed wings among the dead, but with a hygienic colony that's normal. A thin layer of dead bees on the floor is a sign IMO that our bees were good housekeepers.
- Mite Count. There were plenty of dead mites in the debris pile, which is to be expected with any Winter colony. As the bee population drops toward the end of the year, the mites-per-bee ratio goes up. Then as the bees die, the number of mites on the floor will seem disproportionately high.
- Mite Poop. Loads of it! At first glance the brood combs looked clean. When I rotated one so I could see the cell roofs… totally different story. Look at the 11th photo in the slideshow.