I'm of the impression that they have the same spawn rules as the rest of the hostile mobs. IE: the place has to be sufficiently dark... and that's about it. (they obvoiusly would have to 'fit' where the game places them as well)

The reason behind the question is I almost always (say 80% of the time) have spiders spawning along the outside of the east wall of my house, and there seems to be no reason or rhyme to it beyond that. Its ALWAYS spiders, the house is equally lit along all sides on the outside and in. I am unable to provide screenshots unfortunately, but to help give you an idea of the terrain, my house is surrounded by a 2 block deep and 2 block wide trench, with a one block wide 'balcony' directly outside my wall. the trench is surrounded by a fence. I'm stumped. The east exterior is exactly the same as the west exterior. there should be no reason for this.

I'm aware that supposedly spiders could spawn outside my territory and 'hop' over the fence and get in, but why always the east side? I have no problems anywhere else. And why is it only spiders? If it was somehow a lighting issue I should be getting mobs of all kinds shouldn't I?

  • It's possible that you have a one high gap that's below the light level needed to prevent spawns. That would explain why it's only spiders, as they're the only mobs one block high.
    – Mr Smooth
    Jan 5, 2012 at 21:49

2 Answers 2


Only things I can think of:

1) Spiders are the only creature that can climb so the could hop the fence.

2) For some reason you spend the majority if your time on the west side of your house and the area around you that creatures can not spawn in is not reaching the east side of the house as well.

3) All other mobs will vanish in daylight, maybe its the same spiders after they appear once? (If you are not killing them)

4) Trees or a low overhang? Spiders can spawn in 1 height as they just need a 2x2 even floor with 1 block of height, the rest need 2+ blocks but only a 1x1 even floor.

With out being able to see your house these are the best guesses I can come up with.

  • @Mr Smooth the one high gap solution is good thinking, ill relook at my torches and place some more in a few likely places. Ill repost with results.
    – Ender
    Jan 5, 2012 at 22:03
  • 4 is untrue! Spiders need, like any hostile mob, 2 blocks height to spawn.
    – Bogdacutu
    Jan 6, 2012 at 13:51
  • @ mr smooth ive tried everything i can think of with this new information and still they spawn. not sure whats the deal here. when i can post screenshots i will and hopefully that will help bring about a solution. until then... ill just have a spider or two to kill every morning. -.-
    – Ender
    Jan 6, 2012 at 18:56
  • I have come to the conclusion after much experimentation, and even replacign a good portion of the wall with glass so i can see whats happening, that the spiders are spawning beyond my fence normally and then being drawn to that wall because i spend most of my time on that side of the house. Since that was one of your submitted possibilities, answer accepted. thanks for the brainstorm!
    – Ender
    Jan 8, 2012 at 13:25

I have discovered, since accepting James' answer, that Spiders are the only mob that can detect you THROUGH walls. Other mobs, after detecting you through air, can continue to detect you through walls if you happen to run behind one, but Spiders are the only ones that can INITIALLY detect you through a wall. Spidey Sense apparently. This would explain why it was just spiders outside my walls, and not Spiders outside my east wall AND monsters outside my east fence.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .