Logically, Bug should be weak to Poison. Any kind of toxic material is 100x more deathly to an insect due to their small size. And to be clear: I am not saying the same absolute volume of toxicity kills smaller animals faster (which it does). I'm saying that 2 DIFFERENT amounts of toxicity that are adjusted to be the same relative to the 2 animals' different body sizes is STILL more deadly to the smaller animal. Gen I had it right, Bug should be weak to Poison.

Bug should also be weak to Ice. Many animals die in winter but insects in particular are well known to die en masse and get absolutely decimated by the cold. They can't tolerate cold, they go through a holocaust every winter.

And Bug should be weak to Electric. Bug zappers are a well-known cartoonish way of killing insects. It makes just as much sense as being weak to Fire.