That was my question, although the username/question combo wasn’t near as appropriate.
How about a pool of piranha? That should fit reasonably well in a large basement. Just nick up your enemy a bit to get them bleeding pretty good and bind the legs and arms so that they don’t thrash around too much.
Depending on whether the OP is going for entertainment value as well, or merely wants efficiency, one can drop the human visitors into the pit live but tied up, or dead.
Of course, if the “live but tied up”, the bonds would need to be constructed of something the beetles won’t chew through. Would they eat rope? I suspect metal cables or plastic would hold up well enough until the victim no longer had any fight left in him/her.
I’m seconding this. Nasty enough to strip you down to the bone, small enough not to disturb those bones very much, and they’re insects, presumably having quick life cycles.
I don’t know about how fatal they would be, but I would throw some horned toads into your pit.
They spit blood. Out of their eyes, no less.
That way you could scare them half to death, and let the rest of the pit take over.
I’d suggest carrion birds. Large vultures if you can spare the expense, crows if you are more of a budget evil Overlord. Simply tie your victim up on the roof (or in your spacious aviary, again if we’re not sparing any expense) and let the little darlings eat 'em alive. The bones might get scattered a bit, but they’ll be cleaned very thoroughly. I’m told the birds start with the eyes, too. So there’s that wholesome sadistic appeal to it that the whole family can enjoy.
And if you want to get *medieval *on their ass, there’s no shortage of vintage gibbets to be bought, either.
ETA : as a plus side, since they’re outside your palace, there’s little in the way of cleaning the pits, which get smelly. And a bunch of circling vultures over your domain has a definite cachet.
I think beetles, but have some spikes in the bottom of the pit to prepare the object of your displeasure for the insect’s feast.
I’ll third this.
I recall a friend reading (I think, been a long while now) a book called “The Red Tent” and she described a bit in there where this village in Africa had to pick up and move everything they could across the river because a huge swarm of army ants (or some kind of ant) was moving through. Apparently these things are biological Hoovers and just strip everything in their path. Any animal overrun, even big animals, are doomed. She said the villagers kinda liked it since the ants essentially gave the village a super deep clean. Vermin, other bugs…whatever…all cleared away.
So, I think such ants are ornery enough and dangerous enough in numbers and industrious enough to get the job done.
ETA: The scarabs in the movie “The Mummy” looked adept at this. Undoubtedly creative license was taken but not sure if scarabs would really go to town on people like that or not.
Oh, excellent! This way there’ll be blood for them to smell, which one would assume would help them take notice of the newly-arrived dinner.
I still think that the guest should be bound in some way. Hard to drop them onto spikes with enough accurace to be sure that the arms/legs are sufficiently immobilized; if the soon-to-be-dinner is able to flail, the poor beetles might get squashed just for doing their jobs :mad:.
I’m really thinking too much about this, aren’t I? 
I like the way you think !
Only problem with a carrion bird is that the victim needs to be dead first…
I don’t know about rapid skeletonization but they’ll get the job done - even on whales - given enough time. In the meantime, they’re burrowing under your skin to get at the best parts, all while producing gallons of slimy mucus. (Yes, gallons. If you’ve ever held a hagfish, you know that they can produce orders of magnitude more mucus than you could possibly imagine.)
Komodo dragons!
Army ants. Lots of them.
Piranha in a water tank. Need to cut them first.
Not necessarily. He/she just has to be restrained and/or sedated somewhat. Surely the OP has people to do that for him. Besides, if all else fails, I’m sure starvation and dehydration will eventually result in a complacent subject.
I’ve been to Komodo Island to visit the dragons, and I’ve even stood close enough to them to touch them (not that I actually did). They are not a good choice, in any way.
First of all, very hard to obtain, transport and keep in captivity.
Secondly, they do not naturally predate on people, despite all the rumours and despite the occasional fatality which can only be attributed to a rather freakish combination of factors. On Komodo Island itself, kids will carry on playing in the path while dragons walk along nearby, showing complete mutual indifference (I’ve seen this with my own eyes). Dragons want to hunt and kill smaller things, like wild goats or sometimes wild boars.
Thirdly, the dragons only get aggressive and predatory for a short time in the afternoon. They spend all morning in a very sluggish, torpid and normally rather motionless state, ‘sunning’ themselves to get enough energy to go hunting.
Fourthly, if you use more than one of them, it will be hard to stop them fighting among themselves instead of attacking the visitors as intended.
Fifthly, even if you do get the plan to work, no way will you be left with an intact
skeleton. Anything a Komodo dragon kills will look a very sorry mess afterwards.
I know too much about this, don’t I?
But the image of komodo dragons viciously tearing flesh from bodies is so awesome! Can’t you leave me with my fantasy? Or at least come up with a creepy lizard that WILL do my bidding?
You’re right… I apologise for spitting in your cornflakes. Facts be damned. Yes! Komodo dragons! I’ve seen these viscious, bloodthirsty brutes up close and personal and by God, they’d do the job perfectly! You’d see razor sharp teeth and claws ripping into flesh and sinew with astounding savagery, eviscerating the raw, bloodied flesh with the practised ease of a natural born killer, tearing muscle and skin from the clean-pick’d bone with truly horrific speed and sickening thoroughness. They are very much the Terminators of the animal kingdom - vile, disgusting killing machines that knows nothing of restraint or compassion. No problem - give them a small pit area to call their own, toss people in and watch the fun. And dragons are known for leaving the skeleton almost perfectly intact. An ideal choice.