What if there were no spiders?

Spiders have eight legs. Many of them spin webs to catch insects.

Spiders live in gardens, fields and forests. What if there were none at all?

Spiders are everywhere: in gardens and forests, in grasslands and even in the corners of our homes. Scientists have described more than 54,000 different kinds. Many spin silk webs; others hunt by jumping, chasing or waiting in hiding.

Some people find spiders a bit startling, and might think a world without them would be nicer. In this thought experiment, you will find out what spiders actually do, and decide whether a spider-free world really would be better.

The World Spider Catalog lists more than 54,000 described spider species in 139 families (October 2026). Spiders are predators, and together they catch hundreds of millions of tons of prey a year.

This thought experiment removes every spider. It follows three threads: the insects spiders eat, the silk they make and the webs they build. The outcomes are reasoned ideas grounded in measurements, not predictions.

Spiders eat lots and lots of insects. Most of the bugs they catch are insects.

All the spiders in the world eat as much food as all the people eat in meat and fish, or even more!

In 2017, two scientists, Martin Nyffeler of the University of Basel and Klaus Birkhofer of Lund University, estimated how much spiders eat. All the spiders in the world weigh about 25 million tons together, and they catch an estimated 400 to 800 million tons of prey every year.

That is about as much as, or more than, all the meat and fish that people eat in a year, which the scientists put at about 400 million tons. More than 90 percent of what spiders catch are insects and tiny springtails, and more than 95 percent of it is caught in forests and grasslands.

Nyffeler and Birkhofer (The Science of Nature, 2017) estimated, by two independent methods, that the global spider community of about 25 million tons kills 400–800 million tons of prey a year. Insects and springtails (collembolans) make up over 90 percent; spiders in forests and grasslands account for over 95 percent of the kill.

For comparison, the authors note that humans eat about 400 million tons of meat and fish a year. The wide range reflects how much predation rates vary between ecosystems. These are estimates built from field data and models, not direct counts.

With no spiders, many more insects might stay alive.

There might be more flies and more bugs that nibble plants.

Take away every spider, and hundreds of millions of tons of insects a year would no longer be eaten by them. Some of those insects would be eaten by other animals instead, but many might survive and breed.

That could mean more flies, aphids and other insects, including some that eat crops and garden plants. Garden spiders, for example, mainly eat flies, beetles and aphids. Scientists cannot say exactly how many more insects there would be, because birds, bats, ants and other insect-eaters might eat some of the extra.

Removing spiders would remove a predation pressure on the order of hundreds of millions of tons of prey a year, concentrated in forests and grasslands. Insect populations would likely rise, but by how much is unknowable: other predators such as birds, bats and predatory insects might take up some of the slack, and insect populations are also limited by food, disease and weather.

A spider-free world would lose that predation, and any animals that eat spiders might lose a food source.

A spider's web is sticky. Insects fly in and get stuck.

Garden spiders make a new web every day. They eat the old one to use the silk again!

Many spiders build orb webs: round webs with a sticky spiral. The European garden spider builds a fresh web every day. It waits at the center, feels the web shake when an insect lands, and rushes out. Before it builds a new web, it eats the old one to recycle the silk.

Spider silk is amazing stuff. The silk of Darwin's bark spider, from Madagascar, is about 10 times tougher than Kevlar, the material used in protective vests, and it can stretch by more than 90 percent of its length before it breaks.

Orb weavers such as the European garden spider (Araneus diadematus) rebuild their webs daily and eat the old silk to recycle it, as the Essig Museum at UC Berkeley describes; the spider senses prey through web vibrations. These webs are efficient, renewable traps.

Silk also explains spiders' success. Researchers led by Jessica Garb at the University of Massachusetts Lowell describe the dragline silk of Darwin's bark spider as about 10 times tougher than Kevlar and stretchable by over 90 percent; the species spins the largest recorded orb webs, hung on threads up to 25 meters long. Toughness combines strength and stretch.

Hummingbirds use spider silk to build their tiny nests.

The stretchy silk lets the nest grow as the baby birds grow!

Other animals use spiders' work too. The ruby-throated hummingbird builds a tiny nest, only about 5 centimeters (2 inches) across, from plant down held together with spider silk and covered in bits of lichen. Its walls stay stretchy, so the nest can grow along with the chicks. Without spiders, hummingbirds might need another way to hold their nests together.

The European garden spider is harmless to people. Its venom is made to stop insects, not hurt people. It is not aggressive and rarely bites; if it does, it feels much like a bee sting.

Silk travels beyond the web. The Cornell Lab of Ornithology describes the ruby-throated hummingbird's nest, about 5 cm across, as thistle or dandelion down held together with spider silk and camouflaged with lichen; its pliable walls stretch as the chicks grow. A spider-free world would remove that material from their toolkit.

The Essig Museum notes that the European garden spider is harmless: its venom paralyzes insects, it bites only as a last resort, and a bite resembles a bee sting. Seen as a whole, spiders are not pests to be removed but a large, mostly hidden predator guild, a silk factory and a food source for other animals.