You might not like spiders. But you want them in your garden

All habitats depend on predators to keep things in balance. Your garden is a habitat full of wildlife, and while predators like the praying mantis and the ladybug tend to be celebrated, there’s another that’s more often reviled: the spider.

While only a small percentage of the general population has a full-on case of arachnophobia, plenty of people find spiders just plain creepy. They lurk in dark corners, drop from above without warning and have a tendency to go scurrying around in a way many might find disconcerting. Pop culture has long painted the spider as the enemy — a furry, fanged foe to be feared.

But spiders are vitally important, both in your backyard and in almost every corner of the globe. “They are easily, by far, the most important of all predators on insects,” says Rod Crawford, curator of arachnids at the Burke Museum of Natural History and Culture in Seattle. If spiders were to disappear, he adds, “there’d probably be little room left for mammals like us, because we’d be so overrun with insects.”

But in the garden, spiders do much more than just eat insect pests. They serve other ecosystem functions too, including as food for reptiles, amphibians, insects like mud wasps, and birds.

They help birds in other ways as well, says David Mizejewski, a naturalist with the National Wildlife Federation. “Hummingbirds actually collect spiderwebs and weave them into their nests,” he says. “They use them almost like a glue to help pull together fibers and lichens.”

Spiders also contribute, both directly and indirectly, to soil health. Tunneling varieties help loosen soil, and the waste they create — including excrement and the leftovers from their meals — acts as compost.

“Just the sheer biomass of spiders means they have a big impact,” Mizejewski says. “In August and September, all of a sudden people are like, ‘Why are there so many spiders?’ It’s because they’ve had months of reproducing, so there are a lot of them, and all that waste is going into the soil. More than that, with all the insects they’ve killed, there’s a little exoskeleton left, and residual webbing, and all of that is being recycled back into the ecosystem.”

How to build diverse spider habitat

For the biggest benefits, you want a variety of spider species at work in the garden. “Different spiders are going to occupy different zones,” Mizejewski says, and you can help make things friendlier for them from top to bottom.

Up at eye level, you’ll find web-building spiders, including the more than 3,000 types of orb weaver found globally. These common garden residents can get large, but they’re docile spiders that are reluctant to bite. And while their bite — like that of all spiders — is venomous, it’s not generally harmful to humans.

Orb weavers are experts at controlling flying insects like mosquitoes, flies, gnats and moths, and they need tall, sturdy plants to serve as web anchors. “Of course, one thing people always complain about is orb weavers building their webs across a garden path,” Crawford says. “They might attack that problem by knocking the web down, which does no good at all because the spider can build another one in 20 minutes. If you want that web someplace else, you have to actually move the spider.”

Spider relocation is simple, Crawford says. Simply put a container beneath the spider, then “disturb” it, perhaps by jostling the web a bit. “The spider will drop into the container,” he says. “Then you just need to walk to where you want the web to be, and gently shake the spider out.”

Below the weavers, in the middle zone of the garden, jumping spiders hop from plant to plant, hunting mites, aphids and other pests. And on the ground, there’s a whole class of eight-legged predators digging burrows and stalking prey.

“Ground-dwelling species include wolf and lynx spiders, and even — in parts of the West — tarantulas,” Mizejewski says. “These tend to be larger spiders that either hunt actively, running after their prey, or they kind of lie in ambush.”

What those spiders need most is shelter; leaf litter, rocks or even bits of tree bark can provide cover for countless individuals. It also keeps them from drying out.

“One of the worst enemies of spiders is desiccation,” Crawford says. “In human terms, you might think of it as dying from thirst, only it’s worse than that. It’s the entire body losing water at a tremendous rate, because when you’re small, your surface area-to-body volume ratio is much higher. And all spiders, even the ones people consider monsters, are really very, very small.”

Under the rays of the afternoon sun, desiccation can happen fast if a spider has nowhere to hide. Stripping the areas between plants of weeds and leaving stretches of bare ground can create danger zones for spiders.

A simple solution is mulch. Crawford points to a study by ecologist Susan Riechert at the University of Tennessee that looked at how covering the ground with a layer of mulch increased spider populations. “It was amazing how well it worked,” Crawford says. “Just covering the ground between rows of plants enhanced spider populations by 10 to 30 times.”

During heat waves or stretches of especially dry days, you can help the spiders out even more by adding some moisture. “Once in a while, just set your hose on mist and leave it in any area where you’ve established some spider habitat,” Crawford says.

The most important thing to avoid, if you want a thriving spider population, is pesticide. Even spraying for mosquitoes, as many homeowners do in the summer, can be massively detrimental, Mizejewski says. “If you spray and a mosquito goes and lands on that product, yes, it’s going to die,” he says. “But so is the native bee, the monarch butterfly, the firefly and the spider.”

Native spiders need native plants

If you want to help support creatures near the top of the food chain, like spiders, it’s important to support the whole, well, web. That begins, Mizejewski says, with what you choose to plant.

“The number one thing you as an individual can do in your own space is plant native plants,” he says.

Many native plants are host species — meaning they support a specific type of insect — for pollinators. The most common host most people think of is milkweed, the plant that monarch butterflies lay eggs on, but there are lots of other specialized relationships between plants and insects, Mizejewski says. “The caterpillars of a number of butterflies and moths only eat certain plants,” he says. “And there are native wildflowers that have evolved, for example, to perfectly fit the beak of a hummingbird. These things are like pieces of a puzzle, and spiders fit into that. You can’t have spiders unless you have healthy native plant communities to support all the other invertebrates they eat.”

Even those who appreciate the spider’s important role in the garden might still get a bit nervous when they’re face to face with an arachnid. The best way to calm those nerves, Crawford says, is education. He suggests spending some time simply getting to know the spider species in your garden so that when you see them, you’re inclined to protect, rather than pummel, them.

“For people who can be educated on how to deal with spiders, no spider is particularly dangerous,” he says. “No; the really dangerous species is us.”