Do Cave Spider Spawners work by a different set of rules than other Monster Spawners?

Question

During exploration of an Abandoned Mineshaft I found a Cave Spider Spawner. Nothing odd or special about it, but coincidentally my seed has apparently spawned a Dungeon two blocks from it. A Skeleton Dungeon to be specific. Sweet right?

So, I figured I'd torch out the Cave Spider Spawner, and farm the Skeleton Spawner for Bones and Arrows. Except, it doesnt work. I max torched the Spider Spawner, and it still spawns Spiders.

This is what I did to the Spider Spawner:

$ =Spawner
@ =Torches

@@@
@ $ @
@@@

With a torch placed directly on top of the spawner to boot.
-.-
I still get spiders.

I don't want spiders.
Please make the spiders go away.

Do Cave Spider Spawners work differently than Normal Monster Spawners?

Edit: I should note that I do not want to destroy the Cave Spider Spawner, I'm aware that this can be done but its not my objective nor is 'finding a way to make the spider spawner stop' my purpose behind this question. What I'm asking is if the rules behind the Cave Spider are different than the rules behind the other spawners.

Answer 1

The same rules apply to Monster Spawners as to the natural spawning of the mob in question, with two exceptions:

1. Ordinarily, hostile mobs will never spawn next to the player, but with spawners they can.
2. Natural spawns require ground underneath the mob, but Monster Spawners can create monsters in midair.

It is also important to understand the effect of light level: what is relevant is not the light at the spawner but the light at the location where the mob spawns, so putting a torch on the spawner is just a way to center the light, not inherently good — and is in fact inadequate to light up the full spawning range to level 8, though it happens to be sufficient for many natural dungeons. The actual requirement for safety is that the full spawning area (8×8 × 3 high box centered on the spawner's low-coordinate corner) is sufficiently lit (or does not have valid locations to spawn, e.g. is filled solid).

In your case, where you have two spawners right next to each other, there is no way to spawn just the skeletons except by lighting or filling up with blocks the entire spawn volume of the cave spider spawner, leaving you with just a thin slice of skeleton spawner volume (which will therefore have lower spawning rates).

Another possibility would be to construct a sorting system which separates the skeletons from the cave spiders, but I don't know of a particular design to suggest. Cave spiders are particularly difficult to handle because of their small size and ability to climb.

Answer 2

Don't forget that spawners all have a radius in which they can spawn in any dark spot; cave spider spawners tend to be in a network of corridors, where they can spawn spiders on the other side of walls where it might be dark still.