Why aren't ants killed by microwaves? does that mean bacteria aren't killed either?

Very good question!

Microwaves used in microwave ovens have a wavelength of about 4.5 inches. Ants are so much smaller than this that they don't absorb microwaves very efficiently by themselves. The same would be true of bacteria. Microwaves don't directly sterilize things.

However...if the ants or the bacteria happen to be on some food you are cooking, and you got the food hot enough, the high temperature of the food would kill them.

Note that simply reheating food might not be hot enough. It would probably have to be hot enough to cook the food.

So stop putting ants in the Microwave! :)

You microwave ants for a hobby?

Additional

I don't know, maybe something to do with water content. Why do you puts ants in a microwave?

Yes. Cockroaches don't fry either.

they arent dead?

lol why did u even try it? :P