In a quiet corner of your office plant or garden center, a tiny predator is changing what we thought we knew about how spiders kill. Instead of using venom-filled fangs like most of its eight-legged cousins, the feather-legged lace weaver spider (Uloborus plumipes) takes a different—and frankly, disgusting—route to mealtime: it wraps its prey in silk and vomits on it.
That’s right. No venom. Just silk and a toxic spit.
This strange hunting method was rediscovered thanks to an old drawing buried in a 1931 scientific paper. “I was like… what are you talking about?” said evolutionary biologist Giulia Zancolli of the University of Lausanne, Switzerland. While reviewing another lab’s research, she stumbled upon the peculiar reference and traced it back nearly a century.
What she found wasn’t just a footnote in spider history—it was a window into an entirely different survival strategy.
You’ve probably walked past these lace-weaver spiders without noticing. Zancolli and her team hunted for them in landscaping stores and plant nurseries. With delicate bodies and legs that fold in like crumpled leaves, the spiders look more like plant debris than deadly hunters.
But when they catch a fruit fly or other small insect, the real show begins.
First, they mummify the prey in a cocoon of silk, sometimes using up to hundreds of meters of the stuff. No fang strikes. No venom injections. Instead, they unleash the second act of their gruesome ritual: the toxic upchuck.
Most spiders rely on venom stored in special glands and delivered through hollow fangs. But U. plumipes skips all that. When Zancolli’s team looked at their heads under the microscope, they noticed something weird—no venom glands. Where those glands would be, the spiders had rounded blobs of muscle instead.
Digging deeper, the researchers found evidence in the spider’s gut of genes producing deadly toxins. These weren’t injected—they were released from the spider’s midgut and regurgitated onto the prey.
To test how powerful these gut-made toxins are, the scientists injected some into fruit flies. Any guesses what the results were? Lethal. Just as effective as the venom from your everyday house spider.
But if you think these lace weavers spit a small dab of enzyme onto their food, think again. “They slather the silk-wrapped dinner liberally,” says Zancolli. This is no polite drizzle. It’s a full-on toxic coating.
Technically, scientists only use the term “venom” for poisons delivered through a bite or sting. What these spiders use is more like a contact poison, but it’s just as potent. It’s like bypassing the delivery truck and just leaving the poison at your front door.
This unusual kill method is a reminder that nature often has more tricks than we expect. It also shows how some species take the path less traveled—or in this case, less injected.
Zancolli’s findings were published June 13 in BMC Biology, and they might just change how we think about spider evolution. Not every killer needs venom to get the job done—sometimes, spit will do just fine.
So next time you see a delicate little spider resting on your houseplant, don’t underestimate it. It might not bite, but its barf could be deadly.
For more details, please refer to this article published in BMC Biology.
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