Come on now. Think about what you are saying here. A microwave usually runs at 2.4GHz. Same as wifi. The wavelength is about 12 cm.

About how big is a cockroach? About the size of a vienna sausage? Microwave a little sausage and see if it warms up. Microwave a single kernel of corn or a single pea and see if it warms up. Spoilers: they will cook.

The cockroach is alive and can feel pain. It can dodge the hot zones. But eventually it’ll cook too.