Keep an eye on those swarms,
1) AHB may go to ground, but I'd guess a more likely explanation may be that,
2) Mite infested colonies sometimes march out en mass, clump on ground
(usually die shortly thereafter). I've seen this on several occasions.
I have seen pollution stressed bees do this, but usually in small clumps
with the queen, out in front of the hive.
Jerry
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