Ants can avoid microwaves in a microwave oven

Since the wavelength of microwaves is about 5 inches, it is possible for a small insect to avoid the hot areas in an oven (as long as there is no turntable):

(The ant) is able to navigate between the standing waves by sensing the areas where there is high volume heat and low volume heat. You can visualize the patterns of low heat v. high heat by filling a paper plate with marshmallows and putting them in the
oven with the turntable turned off. After a few seconds you will see a pattern of melt or blistering on the marshmallows that are exposed while the others seem unaffected...

A single ant, or even a few ants, can simply walk around between the waves of energy, making their way from one safe area to the next, and avoid getting nuked. If, on the other hand, you put a thousand ants in your microwave and agitate them so that they are running around in a panic, you will, without a doubt, see many of them turned to toast.