What would you do if Zerg invaded Earth?

It is called in-game balance. If the terrans could use the stuff we have, it would probably end all the other races under a second. About biological warfare: I don't think it would have so big effect on the Zerg, I mean they can survive in space. The only thing they are not immune to and is half-biological are nukes. (half-biological because the nature of radiation)

 

And by the way in sc you can only count on the explosion, the radiation is not dangeorus. well its not in at all

 

The radiation should stop zerg regeneration.