Mmmm nope. I did it as a science fair project back in the day :P

Blasted fruit flies for a minute and not a single dead one.

Infact: the microwaves are just a little bigger than the holes in the window on the front door.

So pretty much anything smaller than those holes cannot be heated by the microwave oven. (in air)

Obviously if you put it in a cup of water the water is going to boil.