HomeOutdoorsViralBeware of Hairy Trees, It’s Probably Thousands of Harvestmen Spiders

Beware of Hairy Trees, It’s Probably Thousands of Harvestmen Spiders

by Caitlin Berard
Cluster of Harvestmen Spiders on a Tree, Resembling Hair
(Photo by membio via Getty Images)

Fair warning: if you have any level of arachnophobia, consider skipping this one. With that out of the way, let’s talk about a recent viral sensation on social media – hairy trees. At first glance, it appears the tree (or rock or building) is covered in a thick, wooly coat. In reality, however, it’s an illusion created by thousands upon thousands of harvestmen spiders.

In fairness, it’s a startlingly convincing magic trick. Left alone, the tree truly does appear as though it’s sprouted a flowing mane of dark hair. But all it takes is a gentle prod of a stick (or a finger, for the brave at heart) to reveal the truth of the bizarre scene.

So, what’s happening here? Surely, this is a hoax, right? Nope – it’s actually perfectly normal behavior for harvestmen spiders, otherwise known as daddy longlegs or grandaddy longlegs.

Why Do Harvestmen Spiders Form These Disturbing Clusters?

Interestingly, scientists have long known that this species of spider clusters together in tight groups, they just aren’t sure why.

One theory is that, because harvestmen spiders are prone to drying out, they bunch together for moisture, similar to how other wildlife might huddle for warmth. In forming a group rather than leaving their entire bodies out in the open, they can more easily retain body humidity.

Another possibility is that harvestmen spiders huddle for protection. Unlike their fellow arachnids, grandaddy longlegs neither possess venom nor spin silk. As such, they’re at a severe disadvantage when it comes to warding off potential predators.

However, like stink bugs, harvestmen spiders produce a foul-smelling secretion when threatened. If one spider can produce a nasty smell on its own, a thousand spiders working together can create a smell strong enough to dissuade any would-be predators from enjoying a spindly snack.

Debunking Myths Surrounding Grandaddy Longlegs

We’ve all heard this playground rumor before: grandaddy longlegs (harvestmen spiders) are the most venomous spider on Earth, but their fangs are too short to bite humans. To simply cut to the chase, this is false. But there’s a more interesting explanation than that.

First of all, did you know that the moniker “grandaddy longlegs” is actually used to refer to two different animals? One of these is, in fact, a spider. The other, however, isn’t a spider at all.

Harvestmen spiders, such as those forming the nightmarish cluster above, are not spiders, despite their misleading name. Instead, they’re a type of arachnid called Opiliones. As previously mentioned, they lack both silk and venom glands. Additionally, they have only one body segment and two eyes, barring them from the classification of “spider.”

The cellar spider, also known as grandaddy longlegs, on the other hand, is a spider. Like other spiders, the cellar spider has two body segments, eight eyes, and possesses venom glands.

As harvestmen spiders have no venom to speak of, they obviously are not the most venomous spider on Earth. That said, their defensive odor is toxic, capable of killing spiders and insects, but it’s far from the world’s most potent poison.

Meanwhile, cellar spiders rarely bite – and even when they do, the bite might burn for a moment or two, but that’s the extent of the effects.

The real king of venomous spiders is the Brazilian wandering spider. Resembling a black tarantula, the wandering spider is every bit as dangerous as it looks, with venom capable of killing within minutes. Kind of makes the harvestmen spider look friendly in comparison, doesn’t it?