Keep checking on them periodically. Excessive grooming is often a symptom of some of the common virus`. If you start seeing hairless shiny bees from all that grooming pulling their hairs out .. you know that they have contracted something. Maybe grab a sample of 20 -50 of those weird acting bees and send them for analysis. Check with your regional inspector for the protocol.
Irritations from mites also cause alot of extra grooming. We know you know how t check for those and how to control them.
Otherwise, they just may be feeling frisky or itchy for whatever reasons of whatever they may have got into.
I'll look into seeing if I can get analysis done on them. I am seeing several bees with that shiny look to them, I'm just wondering if that could be caused by the overgrooming alone. I'm planning on hitting all the splits with OAV coming up this week or next while they are broodless, as part of my mite management plan this year, so it will be interesting to see what sort of drop I get when I do that.
A little bit of a rabbit hole here, but I've been reading old ABJs lately, and I came upon an article discussing those shiny hairless bees in the Feb. 1861 issue. The article was debunking the theory that these shiny bees laid the drone eggs in the colony, while the queen laid the worker eggs. I found it interesting that people noticed bees that looked like this before varroa. Obviously there were still viruses before varroa, so it may not say anything either way, but they were common enough that people thought they had a normal function in the colony, and weren't evidence of a sick colony. I just found it surprising.
These bees look like a person would if you dumped a load of ants on them, and they were trying to brush them off while screaming "GET THEM OFF ME!"
I love your descriptions. 
Thanks.
Another thing to remember is that different bees genetically have different grooming habits. People look for good groomers for lower mite counts...just an example, but something to consider if all else looks good inside.
This is a good point, but as I said, this just didn't look normal. This wasn't bees who were a little more interested in grooming, this looked like bees who were desperate to be cleaned off.
Tossing drones is usually weather/climate conditions (cold, wet, dearth) , or the hive simply felt they were carrying too many, or the drones had whole tag teams of mites on them and just died off.
Your bees may also be responding to the dearth by cleaning out drones. Drones are a drag on the hive if there isn't enough food.
Based on the fact that both halves of the split have the piles of drones, and only one half of the split and now another hive without a pile of drones are doing the overgrooming, I am pretty well convinced that the drone dumping is just a genetic thing with these new bees and has nothing to do with the overgrooming. As HP said, it seems like a response to the dearth.
A small hive may have experienced robbing and that would account for the dead bees.
I have been keeping pretty close of an eye on the splits and haven't seen any robbing, and I'm also not sure why robbing would result in mostly dead drones as opposed to workers, so I'm fairly sure that robbing isn't a contributing factor.
I would advise that you not reduce queen cells in the future. Let them decide who lives a dies. It won't make any difference in the hive and you are more likely to get a good queen.
I have done this before and have gotten swarms when I did, and I also had one hive basically swarm to death. I do always leave a couple, usually 2-4 so there is still some competition, but I don't leave them all anymore.
Lotsa possibilities, few data points.
Let us know what you find inside when you do a deep dive again.
I certainly will keep everyone informed on what's going on and thanks for all the responses. It's one of those mysterious curveballs bees can throw at you. We'll see if we can untangle the situation.
