Why the heck are they humanoid?
Also, poison and fire are usually quite good for swarming enemies. Might be bad for the surroundings for a while, but better than dying.
@SingLove
Honestly? They couldn't possibly be humanoid and keep their ant characteristics without the plot umbrella of 'magic'.
Even in prehistoric times when the oxygen content was higher and there were fewer birds to kill them off, the largest ever insect was a dragonfly. And it was only around the size and weight of a crow.