I'm building a spider spawner exp farm, and I have everything planned out.

Now the only thing is to build it. But what material should I use?

Are there any blocks that a spider (either type) just cannot hold on to the sides of?

My farm should function if there are none, but it would be a huge boost to convenience and efficiency if there are any such blocks.

Keep in mind that this question is not the same as this question which just asks how to make your house safe from spiders.

  • Would you mind posting a screenshot of your farm? I may be able to help if I knew what I was working with. – Jonny May 15 '12 at 20:27
  • @JonnyB It's just a square 8 wide by 4 high with water on the bottom and the spawner in the middle (so that every spawning space is available to spawn). The only reason that I want blocks they can't climb is that they can fight the streams and track me through blocks, and if they climb a wall, sometimes it takes them a long time to get out of the spawners range. – Mr Smooth May 15 '12 at 21:02
  • ok, if you are 1 of those guys that have a wall for some reason and you dont want spiders over in it, then here is an idea put cactus on the wall and since you cant put cactus next to each other, make it diagnally – user27287 Jun 8 '12 at 20:36
  • Have you considered removing the layer of wall blocks just below the ceiling? That would give less room for the spiders to climb and make it possible for them to track you. Or can spiders fit through a space like that? – Sadly Not Sep 14 '12 at 22:27

Cover the walls with signs. Spiders can't climb a wall if it's covered in signs. I just tested it.

  • 1
    Confirmed! Though signs don't appear to be unclimbable exactly, just somehow interfere with climbing: One level of signs doesn't stop them, but two above their heads does… mostly. If a spider is "bounced" from being hit or is standing on another spider, then even two levels of signs isn't enough. But for a close-topped spawner room, covering the walls entirely should help keep them down. – SevenSidedDie Sep 15 '12 at 0:22
  • This is the correct answer, it should me marked as such @Mr.Smooth – Ender Mar 25 '13 at 9:31
  • 8
    This answer is no longer valid. Note that I have yet to test up to what version it is no longer valid let alone what version it IS valid in but it is at least no longer valid in 1.12+. – Brandon Rankin Jul 10 '18 at 18:34
  • 3
    It does not work. Just tested in 1.15 java version – Adam Bajger Jun 18 '20 at 19:45

Spiders can climb:

  • Any solid block, that is, one that obstructs the players movement. This includes 'solid' blocks such as stone, wood, dirt etc. as well as 'transparent' blocks such as fence, glass panes and iron bars.

  • Ladders and vines, exactly as the player can.

Spiders cannot climb:

  • Blocks which do not impede the player, such as grass, sugar cane, fire or flowers.

  • Water or lava, but will behave as other mobs (swim/drown, burn).

  • Nether portal blocks (they can climb the surrounding obsidian though).

  • I assume by "creeper" you mean "vines"? ;) – gnovice May 14 '12 at 15:43
  • 4
    So there's not a single building material that a spider can't climb? Well that sucks. I'm going to leave this open for a while longer though, in case someone's figured out a way to stop them from climbing. – Mr Smooth May 14 '12 at 21:00
  • 5
    Well.. It's like in real life, spiders can climb almost anything haha :D – Depado May 16 '12 at 7:46
  • I tried out some more stuff that doesn't work: Rapidly extending pistons "throw" them off, dropping them back down, but eventually, they are still able to escape. – SingleNegationElimination Jun 9 '12 at 16:30
  • Wouldn't 'nether portal blocks' fall under the 'blocks which do not impede the player' category? – Christopher Berman Nov 27 '12 at 1:01

They can climb any solid block. If you want to stop them from escaping, make an overhang inside the trap like so:


X=solid block.

  • 7
    This isn't what I'm looking for, I've got an enclosed room, they can't escape even if they do climb, but I'm looking for building materials that they physically can't climb. – Mr Smooth May 14 '12 at 20:58
  • Overhang allows mobs to alter their fall trajectory – Tomáš Zato - Reinstate Monica Jun 18 '15 at 12:13

You could build something like this B=Brick

B.                              B  
B.                              B  
BB.                         BB  
B.                             B  

Spiders can not climb over overhangs so just put a brick on the 2nd block to keep em down. Hope this helps.


While spiders can climb cactus blocks, they will eventually be killed while doing so.

  • 4
    They can climb cactus, they just get injured in the process. – fredley May 15 '12 at 10:30
  • @fredley that doesn't make them fall ? Haw. I thought. Thanks for commenting ^^ – Depado May 15 '12 at 11:24
  • 2
    @Depado it will not knock them off. I have spent many moons in creative mode, tricking spiders into climbing cactus in the false hope of destroying me. only to die from the spines imbedded in them. – legacy May 15 '12 at 19:30

Not the answer you're looking for? Browse other questions tagged or ask your own question.