Spiders, specifically, are mentioned several times throughout Harry Potter and the Chamber of Secrets as running away, not just all creepy, crawly critters. I looked up basilisks and see other parts of their description mentioned (such as the roosters), but nothing related to spiders.

Is a reason given as to why basilisks are mortal enemies of spiders?

2 Answers 2


It’s not stated in HP canon, but this enmity goes a long way back.

The exact reason is never given in the Harry Potter canon, but we can make a guess:

  • Basilisks can kill you with eye contact. That’s very unusual. I can’t think of any other creatures that can do that (at least in the Potterverse).

  • Spiders have many unclosable eyes.

    The eyelid is mostly found in mammals; a lot of other animals have no need for them. That includes spiders and insects – there’s nothing covering their eyes. So just being in the presence of a basilisk is dangerous – they have all-round vision, and they can’t close their eyes. (On the other hand, a spider against a Weeping Angel?)

But is that enough to make them mortal enemies? That’s unclear.

When Harry and Ron encounter Aragog in the forest, he’s blind, but clearly still scared of the Basilisk. It’s possible that there’s no longer a rational reason for the fear, but has simply become something baked into the spider psyche.

The idea of spiders fleeing basilisks is hardly a new one. In Bulfinch’s Mythology, a nineteenth-century retelling of classical mythology, we find the following passage:

The basilisk was of some use after death. Thus we read that its carcass was suspended in the temple of Apollo, and in private houses, as a sovereign remedy against spiders, and that it was also hung up in the in the temple of Diana, for which reason no swallow ever dared enter the sacred place.

The same passage states other facts about the basilisk that are repeated in HP canon – for example, the red plumage, or being hatched with a chicken’s egg under a toad – but doesn’t provide a reference for this passage.

Bulfinch is supposed to be a retelling of existing stories, so we could probably trace this back into other classical sources, and we might find a reason there. Unfortunately I don’t have time to do that right now – exercise for the reader? :-)

  • There's mention of red plumage on the basilisk in the Harry Potter series? I must have missed that… (Also, the ‘mortal enemy’ wording is, as far as I can recall, not used in HP; it just says something like “a creature we spiders fear above all others”—which is certainly an understandable description of an animal whose very presence in the vicinity almost unerringly means instant death to you.) Aug 22, 2015 at 10:09
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    @JanusBahsJacquet 1) I was looking at Fantastic Beasts when I mentioned red plumage; that's where that comes from. 2) When Harry and Ron are reading the textbook in Chamber of Secrets, it says “Spiders flee before the Basilisk, for it is their mortal enemy”.
    – alexwlchan
    Aug 22, 2015 at 10:32
  • Sounds like a Basilisk would be an ideal pet for those who don't like insects in the house. Living with it would be somewhat like eternally house breaking a puppy, but with more serious side effects. Also, +1 for the Weeping Angels reference!
    – FreeMan
    Oct 16, 2015 at 13:48

Because spiders have 8 eyes

Imagine trying to avoid looking at a basilisk when you have 8 eyes! Especially when they have 360 degree vision and, as pointed out by Ixrec, these eyes cannot be closed, it makes it practically impossible to avoid seeing a basilisk if they are around. That's why spiders fear a basilisk above anything else - they don't have any chance to defend themselves at all!

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    Lol. Was this explained in the book and I just missed it >.<
    – kjw
    Aug 22, 2015 at 6:37
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    "Harry spun around. Feet away, towering above him, was a solid wall of spiders, clicking, their many eyes gleaming in their ugly black heads …"
    – Valorum
    Aug 22, 2015 at 8:04
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    So simple, yet so obvious. I always just accepted the enmity as fact and never paused to consider why, but this makes so much sense. +10 if I could. Aug 22, 2015 at 10:07
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    Probably should mention the eyes are uncloseable, that's at least as important as the number of them.
    – Ixrec
    Aug 22, 2015 at 13:18
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    According to Wikipedia and BugGuide most spiders have 8 eyes indeed. However, there are also spiders with 6, 4, 2 or 0 eyes.
    – Oriol
    Aug 22, 2015 at 21:39

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