You've gotta use dirt to camouflage the hole. So, what kind of prey are you after? That oughta do the trick. You can also make it so it's remote detonated.Wire traps work excellent with this sort of thing. You can also make an obvious hole to goad someone into jumping into the actual pit.Wha--?!
Nobody's gonna fall for such an obvious trap.HehehehHm? What're you doing?