I don't think your team total hp cannot be dropped to 1% with bees, at most I got to tank the bees, got my team total HP dropped into 15/20% and never gotten any lower even though they hit more bees

I think the team i mentioned got its hp drop a bit before got caught to bugs but other situation isnt that impossible too. Imagine your team caught in a loop like in the third event map, then constantly attacked by the bugs.