If i drop a cockroach....

[lgas]

That makes more sense. The way your post was worded it seemed to me you were trying to suggest that it's terminal velocity was low (ala the string experiment) and therefore it would die easily.

FWIW, I agree that it seems likely that there is no height you can drop a cockroach from that will kill it... although dropping it from a great height into a volcano should do the trick.