Gather evidence at the scene. Do your best to figure out what happened. Other bees’ lives may be at stake, should you disregard the clues.
Hives that die in winter don’t usually perish of American Foulbrood, but still, you want to rule that out as a cause of death. AFB is rare, but it is very serious. When you take the cover(s) off, take a whiff of the air inside the hive. Sure, it’s likely to be musty-smelling, but AFB has a distinctive pungent odor that can tip you off to a lingering threat that dwells within. If there was any brood in the frames, you’ll want to examine it closely for the tell-tale sunken, perforated cappings…but again, a winter kill could have some dead capped brood and still not have AFB. Are any pupal tongues discernable? I’d be very anxious if I saw that…even in a hive that died in winter. If you suspect AFB, consult a mentor and/or the state bee inspector, and shut the hive up tight. If it is indeed AFB, you’ll want to burn the frames, wax, and bees, and scorch the inside of the hive bodies…or play it super safe and burn the lot and get new.
OK, so it’s doubtful that you’ll smell or see anything AFB-like (but you always want to be looking for it). Separate the frames and have a look – the quietest inspection a beekeeper can do, looking through a dead hive. Assess the bees on the comb and those on the bottom board. How big was the cluster? Can you tell from looking at their bodies if they fell away slowly over time, as opposed to dying at close to the same time? That could make you think of mites – tracheal and/or varroa – versus starvation. Bees share their food with each other, so they all live until the food runs out and then they die together. Did these bees have honey? There may be a little or a lot of honey in the hive, but if the cluster wasn’t in contact with it…if the cluster was even an inch or two away, then it’s possible that the bees starved with food just out of reach. Bees in the cells of the comb, headfirst, also indicate that they died of starvation, searching the cells within the cluster for sustenance. Work your way through the hive. Do you see the queen anywhere? If she’s not there, you can’t be sure what happened. She may have died early or late, she may have been alive until the end but happened to evade discovery during the autopsy. But if you should find her, then you know that the hive wasn’t queenless. Examine the bees on the comb and on the bottom board. Do you see varroa mites on them? The varroa may be wedged between the plates (tergites) of the bee’s abdomen. If you find varroa on the dead bees, and you treated with something in the fall you might wonder if the treatment failed. Perhaps the mites were resistant…note to self: use something else this season. Even if you don’t see varroa mites on the bees, you can be sure there was some level of mite infestation the previous season, and those mites created opportunities for viruses. These viruses degraded the bees’ immune system, and shortened their life span, leaving a winter cluster of bees that didn’t live as long and whose vigor was reduced. A hive that dies of what looks like starvation may have, in fact, died of a combination of virus-caused shortened lifespan and starvation.
Are the bees’ bodies torn up? Are there a lot of wax cappings and other debris on the bottom board? Perhaps this hive was weaker than its neighbor and was robbed out. Pushed over the brink by robbers next door.
As long as there’s no sign of AFB, the final steps are the same. Brush the bees off the combs and out of the hive. Leave the ones in the cells – the new bees will clean them out without damaging the comb, where you’ll just make a mess of it.
Close off all entrances to avoid having bees from the area get in the habit of raiding this hive, and to avoid mouse damage. Some gray-green surface mold may form on the combs, but don’t worry about that. Again, the new tenants will clean it up. Make plans to obtain new residents to repopulate the hive.
Spring-cleaning a dead colony is a sad task, but take some time and give it some thought. Learn what you can, and then move on. Words to live by, really.