I've lately seen a lot of instances where a leaf is dangling from a piece of web coming down off a tree. What purpose/s does this serve for the spider? Is it some sort of mechanism for the spider to determine the wind / disturbances in that region?

I've seen a suggestion that it's to help act as a plumb during web construction to keep part of it tight, but do we actually know for sure?

Here's a national geographic image showing what I mean: enter image description here http://ngm.nationalgeographic.com/ngm/photo-contest/2012/entries/177963/view/

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    $\begingroup$ I would think that these leave simply got caught by the net. $\endgroup$
    – Chris
    Sep 20, 2014 at 18:04
  • $\begingroup$ It's attached to a single piece of thread, dangling about 5ft from the ground. $\endgroup$ Sep 20, 2014 at 18:09
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    $\begingroup$ Could the spider have used the leaf as support for the web while it was still attached the tree, then the leaf fell off the tree and still hung on the web? $\endgroup$
    – user137
    Sep 20, 2014 at 18:30
  • $\begingroup$ @user137 interesting idea, and would explain why I only see it in autumn. It wouldn't have to necessarily be part of the web for this to be viable. $\endgroup$ Sep 20, 2014 at 18:47
  • $\begingroup$ I've also come to reason that spiders use web to move from leaf to leaf, so it may just be a leaf that's had web shot onto it by the spider and was attached to a more permanent part of the tree. $\endgroup$ Oct 10, 2014 at 18:43

1 Answer 1


As far as I know, it has a practical effect. Spiders hunt for small insect and don't like when bigger animals damage their webs. So that they make the web visible for mammals, but in the way which doesn't prevent the prey from being caught.

I don't have reference for this, my colleague (entomologist) told me so.

  • $\begingroup$ I like this thought. It's like the owl decals we put on windows to keep the birds from banging their heads on the glass. I, for one, won't walk into a web I know is there. $\endgroup$ Nov 12, 2015 at 23:42
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    $\begingroup$ It would be good to have a reference for this claim or to clarify that this is just a guess. $\endgroup$
    – Remi.b
    May 31, 2018 at 15:53

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