Since my current story has characters with superpowers, they are capable of dealing with them but their personalities make the outcome vary. It's also an interesting question so I'd like to elaborate on it
I'll only talk about the main characters' different reactions (I'll add the headshots so the long text doesn't look bleak):
Brick: Would probably hide inside a river or some place until the bees go away. He is powerful enough to kill them (he has sound abilites and could probably just make them explode from the inside or blast them away cause #superpowers) but he is also sensitive to sound (psychological reasons) and would be pretty disturbed by the sound they make, he feels distressed with white noise and the sound bees make would terrify him, so, escaping/hiding is his best course of action unless he needs to protect one of his brothers or something like that. Basically, unless he is forced to, he'd probably just hide. (If he couldn't use his powers for any reason, he'd still look for somewhere to hide and if that's not possible he'd probably get stung by all of them and have bumps all over. He wouldn't die, but he'd be pretty angry at the outcome xD)
Butch: He can make a force field powerful enough to protect himself, so the bees would probably stop chasing him eventually if he can just get far away enough. He can also absorb positivity/life force so he could just kill the bees, but he is aware bees are important and wouldn't want to kill them (he wouldn't admit his reasons to his brothers though). He would kill them if left with no other choice but yeah, he'd rather fly away than deal with them, haha.
If he is unable to use his powers for some reason, he'd try to hide, if there's a body of water he can hide there, he can hold his breath the most between his brothers so he would probably survive the attack XD otherwise he'd be stung and be all like "dammit" but not on the angry side, just annoyed at his useless attempt at escaping.
Boomer: he'd have it easy since he has the ability to talk with insects and he has electricity as his superpower, so, he can just threaten them. I doubt the bees would still attack knowing he can fry them all lol. He could actually manage to convince them to do his bidding and redirect their attacks towards someone else if he feels vindictive enough.
If he couldn't use his powers, he'd probably just let the bees sting him and not really care. As Boomer can't feel pain, he'd be covered with bumps but wouldn't think so much about it.
Barricade: He is terrified of bees, although he has fire powers, he'd probably run away and hide as well unless he is backed into a corner in which he would then burn all of them out of panic.
If he can't use his powers, he is pretty much doomed XD He has a frying pan as his weapon, so, he can't do much with that and being powerless lol, maybe if it was a few but 10,000 is too much lol He'd probably just faint out of fright.
Brazen: He is pretty respectful of nature so he wouldn't want to kill the bees. He absorbs negativity from others and the environment thus he can solve the situation simply by getting rid of their anger.
If he couldn't use his powers he could also get away by holding his breath, but if not able to hide he would get stung and just stay whiny about the experience, being sulky or in a bad mood XD He'd probably use the situation to be pampered and comforted by Barricade (his brother).
However, Brazen is immune to poison so the stings wouldn't make him be in pain or have swelling, he'd just experience the pain from the initial piercing.
Bruise: He would not really care about them being bees and nature being important but he'd probably just freeze them a little and then get as far away as he can.
He'd probably be okay if the bees attack him, his skin is hard to pierce so the bees wouldn't be able to hurt him.