The Secret Behind the Creation Of Cobwebs

The majority of cobwebs are actually formed from abandoned spider webs. These home-abandoning spiders, mainly those of the species Theridiidae, build these sticky webs for catching prey.

Cobwebs are terrific reminders that it is time to clean that difficult spot. These pesky webs form in the corners of our rooms, along the edges of ceilings and on the sides of our walls. You can get rid of them easily, but without fail, they seem to come back in no time!

The common assumption is that these cobwebs are formed out of the blue, due to dust particles adhering to each other (maybe they’re just lonely). However, cobwebs don’t spontaneously form. The real secret behind cobwebs is actually far more creepy.

Cobwebs are the work of spiders

As it turns out, the majority of cobwebs are actually formed from abandoned spider webs!

That’s right, these home-abandoning spiders, mainly those of the species Theridiidae, build these sticky webs for catching prey (spiders also use their silk to make cocoons for their eggs). Over time, however, dust accumulates on the web, and the spider has to abandon it and build a new one. That’s the reason why you never see a spider on a cobweb, even though the eight-legged arachnid is responsible for its creation!

Also called cobweb spiders, these spiders make a tangled web formation which doesn’t have any discernible pattern. The many spiders that come under this family (close to 3000 different species) and they all make wide and varied webs. But there are some commonalities for the most part.

Most are adept hunters and the ones that do make webs to catch prey, intentionally make them a tangled mess. They anchor their webs to support structures like beams and corners of walls, building a 3-dimensional snare. This snare then ends up as a common household nuisance once it serves its purpose to the spider.

The ends of these webs, when they are active, have sticky droplets to glue unsuspecting insects like flies to the web. The same sticky property of the web also attracts dust and pollen. These agents tend to damage the web.

What About Single Strands of Dust?

Okay, so now we know that the haphazard cobwebs were once active spider webs, but what about those single strands of dusty material that are seen hanging from the ceiling? Are spiders responsible for those too?

In fact, they are. Spiders, as well as a few other tiny arthropods, have the ability to produce silk strands for travel and protection. Spiders specifically use this strand of silk as a safety line when they jump or swing from place to place.

The technical term for spiders travelling using silk is ballooning. It’s a bit like Spider-Man, if you think about it. Or rather, Spider-Man behaves like spiders!


Credit: Alexandra-Auditore/ DeviantArt

These silk strands are different than those the spider uses to make their webs. The silk they use to balloon is dragline silk also called ampullate silk. This is not the only use of dragline silk but is also sometimes used as a scaffolding for the web.

Again, these left-over strands of silk gather dust over time, resulting in those single irritating dust strands that we’ve all walked through and had a miniature tantrum trying to pull them off our face.

Don’t cobwebs degrade?

An even more fascinating curiosity is how long a cobweb lasts. Spider silk is a tough, strong, and hardy material. Scientists have been trying to replicate its tensile strength and elasticity for a while now. This strength also gives it certain immunity from degrading.

Though dust and pollen harm the web, making it useless for the spider, it doesn’t just crumble after the spider isn’t there to tend to it. A team of scientists studied the strength of 4-year-old abandoned spider silk and found that though its mechanical strength had reduced, it was still pretty strong.

Spider silk can be degraded by enzymatic action (spiders can eat their silk after all), environmental degradation is much slower. The silk strands are made out of complex amino acid crystalline structures that make the silk very durable.


Spiders are the secret behind the dust streamers decorating our homes. As strange as it may sound to some people, perhaps spider-enthusiasts may find cobwebs interesting, as they can be used to track the movements and web-building habits of spiders. Or maybe not.

Spiderwebs are very difficult to spot due to the razor-thin strands of which they’re made, and by the time you do spot them, the spider is likely gone and the web is already lined with dust, abandoned for a newer home!

Suggested Reading


  1. University of Kentucky
  2. The Tree of Life Web Project
  3. ScienceMag
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About the Author:

Brendan has a Bachelors of Science degree in Biotechnology from Mumbai University (India). He likes superheroes, and swears loyalty to members of the Justice League. He likes to take part in discussions regarding the human body, and when he is not doing that, he is generally reading superhero trivia.

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