This is a dump of information I hope can help. I have two hives. Both are top bar hives. One is doing phenomenally well. My other hive, kept on a blueberry farm about 20 miles away, not so well. I noticed a gradual decline in population in this hive, nothing sudden like a swarm. Some of the bees, especially the drones are jittery and shake while walking, a behavior that is not consistent with the previous hive or my other hive. There seems to be an over all sense of confusion throughout the hive. Bees wandering aimlessly around the back of the hive as if they're lost. Extremely calm, almost unaware I'm there. 1 bee may shoot out zigzagging as if upset, then flys off. Bees in the roof (sort of like an attic), also wondering aimlessly as if they are looking for the entrance. (never saw this before nor in my other hive) A few bees laying here and there on the bottom of the hive lethargic and barely moving, their tongues sticking out, brown in color. There is tons of clover around the blueberry fields and this hive had lots of pollen stored up and even a couple of areas that has capped honey so starvation shouldn't be the cause. The queen is laying eggs and there is brood. However, if this trend continues I suspect the hive is doomed. It's like slow death.
I don't know what they could have gotten into, but the blueberry farmers do use a pesticide. I don't know what it is or if they changed it. The year before I had a hive that did very well but didn't survive a freak freezing rain storm and ended up getting robbed by an unknown honeybee hive somewhere nearby towards the tail end of winter and unfortunately starved.
Also, I also noticed some bees are overall smaller in size, covered in grey hairs. They seem to die first. One other dead bee seemed to have smaller than normal middle legs. I'm not sure if this is a result of some genetic anomalies.
Any information is appreciated.