How Do Spiders Benefit the Garden?

Spiders get a bad reputation, but they’re actually one of the most voracious predators of garden pests. There are over 45,000 different species of spiders known globally, but less than 30 of them are venomous. That means less than one-tenth of a percent of spiders are dangerous to humans!

While they pose little risk to people, pests like aphids, beetles, mosquitoes, flies, and wasps should be terrified of spiders. These eight-legged arachnids are hungry predators, weaving webs to capture their prey and sometimes hunting them down. Spiders are among the best pest control officers around and a very important component of a biocontrolled eco-friendly garden. 

If you want to reduce or avoid pesticides and grow a more ecological garden, spiders should be your new best friends. Instead of fearing these creepy crawlies, let’s dig into the benefits of welcoming them into your garden. 

The Long Answer

Nobody wants to walk head-first into a sticky spider web, but the presence of these intricate traps indicates that you have high-level predators in your garden. If you regularly see webs strung between your tomato plants or scary-looking spiders running across the soil surface, here are the main reasons why you should celebrate rather than fear them.

Free Pest Control

Research proves that spiders are among nature’s best pest control agents. Their voracious appetite for insects means they are continuously attacking the pests that cause humans the most problems.

In organic gardens, spiders are particularly important because they create ecological balance without the need for pesticides. These predators hunt their prey or lure them into webs so they naturally control the populations, preventing infestations from taking over your garden. 

If you have enough spiders and other predatory insects (like ladybugs, syrphid flies, and parasitic wasps), you may not need to apply pesticides at all. In fact, applying broad-spectrum pesticides can kill spiders and cause things to fall more off-kilter. Without natural predators to eat the pests, harmful insects can rapidly expand their populations, forcing gardeners to get stuck on a “chemical treadmill” where they have to continuously spray to protect their crops.

Fortunately, embracing nature’s free pest control is quite simple. You don’t necessarily have to plant certain flowers or install any sort of house to attract these predators. Spiders naturally find their habitat amongst garden plants and enjoy building their webs while suspended between two surfaces, such as branches or twigs.

Reduced Risk of Plant Diseases

As spiders control garden pests, they simultaneously reduce the risk of crop diseases. Many plant pathogens are spread by insect vectors such as aphids, whiteflies, and mealybugs. The pests are considered vectors for disease because they spread viral, bacterial, or fungal infections whenever they feed on new plants. Insect-vectored crop diseases include tomato mosaic virus, asters yellows, leaf curl virus, and greening disease of citrus.

This is where the spiders come in. As their intricate webs capture these pests and they consume the helpless bugs, they effectively stop the spread of any disease-causing pathogens that may have been inside the pest. As a result, gardens with high levels of spider predation naturally have lower levels of plant disease. In simpler terms, more spiders means fewer diseases. This can significantly improve your yields and eliminate the need for chemical fungicides or other sprays.

Ecological Balance 

Your garden is more than a food-production zone; it is its own ecosystem! The biodiversity of your garden’s ecology directly contributes to its resilience. A more diverse garden is more resistant to problems such as drought, extreme weather, pests, diseases, and crop failures. Spiders add biodiversity while fueling the natural food web of the native landscape.

Spiders are an important food source for local animals such as centipedes, birds, and lizards. These animals contribute to a diverse, interconnected, balanced ecosystem. Small insects are consumed by spiders. Then, spiders are consumed by birds and lizards. As the food chain moves upward, those smaller animals are consumed by larger animals like bobcats, coyotes, and hawks. 

The benefits continue to compound as you zoom out to look at the broader role of spiders in the ecosystem at large. A balance of each of these species creates a complex network of flora and fauna that provide many benefits, including built-in pest control, pollination, recycling of nutrients, and wildlife viewing.

Aerated Soil

While many spiders contribute to above-ground garden benefits, underground arachnids like wolf spiders actually improve the soil. Aeration is the key to healthy, rich garden soil. Aerated soil is fluffy, loamy, and easier for plants to grow in. Soil without aeration is compacted, hard, and difficult to work with. As ground-dwelling spiders tunnel through the soil of your garden beds, they loosen the soil to create more pathways for water and air to reach plant roots.

At the same time, underground spiders aid in the complex biology of the soil food web. Most of us don’t realize that there are billions of microscopic organisms interacting with our plant roots at all hours of the day and night. These predominantly beneficial microbes include bacteria, fungi, protozoa, and beneficial nematodes. 

Spiders feed on these organisms, aiding in the recycling and decomposition of dead plant and animal materials. In turn, nutrients can move through the soil ecosystem and become available to plants. The spiders become food for larger underground mammals, which aerate the soil and poop out more nutrients, perpetuating the natural cycle.

Types of Garden Spiders

Most people fear spiders because they group them all together. They assume that any spider could be poisonous, like a black widow or a brown recluse. The truth is that less than one-tenth of a percent (0.1%) of spiders are harmful to humans. The majority are very beneficial. The key to deciphering between the two is knowing how to identify spiders in your garden.

Most spiders fall into one of two categories:

A diversity of spiders in both categories creates the most benefits for your garden. Here are some common species to look for:

Orb Weaver or Garden Spider

One of the most common garden spiders in North America is the orb weaver. It is aptly named because its webs are elaborate and concentric, with circular orbs radiating outwards. They include many species of the Neoscona genus, most of which are colorful and large, with yellow or black stripes and spots.

These spiders wait in their webs all day and night for prey to become entangled in the silk. They are docile and not aggressive towards humans. 

Wolf Spider

Recognized by their elongated hairy legs, these hunter spiders are mostly found running along the ground. They are truly the wolves of the arachnid world, as they are furry, they run very quickly (up to 22 mph!), and they don’t build webs. However, some wolf spiders will weave a silky retreat where they return after hunting down prey. 

These arachnids don’t threaten people and are not poisonous. They sometimes jump if they need to catch prey. The females will carry their young perched on their backs. You definitely want wolf spiders in your garden because they are aggressive hunters of grasshoppers, earwigs, crickets, flies, and ants.

Sac Spiders

These spiders are named for the fat pale sac on their backside. They are about the size of a nickel and can be bright yellow or bright green. Sac spiders live in gardens and sheds across the world. They create silky tubes between structures, beneath plants, or on the bark of woody perennials. 

Unfortunately, some sac spiders will bite humans (and can be painful), but the venom is not harmful to humans. These nocturnal creatures are mostly active at night when they hunt all sorts of insects in the garden. 

Daddy Long Legs

Also called cellar spiders, we’ve all likely seen the famous daddy long legs around the garage. There is an urban legend that these spiders have the most potent venom, but in reality, their fangs are too tiny to even bite a human.

Instead, these skinny creatures hang out in dark corners or underneath logs, feeding on tiny flies, mosquitoes, ants, and any other insects that wander into their messy webs.

These spider-like creatures aren’t actually spiders, but opiliones. While they’re in the same family as spiders, they don’t feed on live insects. Instead, they consume decaying plant matter, dead insects, and fruit. This makes them important garden cleaners.

Crab or Flower Spiders

These species have enlarged front legs resembling crab claws (but not quite as “pinchy”). They are hunter spiders you are more likely to see in the garden because they’re active during the day. They especially love mulched or grassy areas where they can attack mites, wasps, mosquitoes, flies, beetles, and other small pests. They are sometimes called flower spiders because they will wait for their prey while sitting on flowers.

Jumping Spiders

These hairy black or shiny spiders hunt during the day and pounce on their prey. They are great predators of common nuisance pests like flies and mosquitoes. These predators do not spin webs, but they may make silken hangouts under bark or leaves, which is why mulch is important. Jumping spiders especially love roaches, worms, moths, and crickets.

Lynx Spiders

These bright green spiders are a mashup of good and bad. They eat a variety of insects, including annoying caterpillar larvae that often attack brassicas and corn. However, lynx spiders sometimes prey on bees and wasps, which can be problematic for pollinator gardens.

These spiders rarely bite humans and are not dangerous. They are typically well-camouflaged amongst plant foliage and hunt their prey without a web.

How to Embrace More Spiders for Garden Benefits

Spiders provide lots of benefits for very little effort. Embracing these creatures requires a mindset shift away from fear and towards curiosity. Here are a few ways to welcome these natural pest control agents into your garden to create a healthier, balanced ecosystem:

Prioritize Diverse Plantings

A diversity of crops, flowers, shrubs, and trees creates a multi-dimensional garden with a wide range of insects and habitats. Diversity is better than monoculture (planting large pieces of land with just one or two species) because it promotes a more sustainable ecosystem that can function without as much human interference. For spiders, diverse plantings mean more places to hide and hunt and a wide range of food sources.

Avoid Chemical Pesticides

Pesticides don’t just kill pests; they harm beneficial predators, too. If you want to create a more natural bio-controlled garden, it’s essential to reduce or eliminate chemical pesticide sprays in your garden. These chemicals will kill spiders and make it more difficult for them to return to the garden to serve their pest control duties.

Leave Webs Intact

Whenever you encounter spiders, consider leaving them undisturbed so they can do their job. Most spiders don’t want to hurt you. Rather, they want to attract insects for a feast. Spiders spend a lot of energy and time weaving silky webs to trap their prey.

Imagine spider webs like natural insect sticky traps; they are working in your favor to capture annoying pests! It’s OK to knock down a few webs on accident when moving through your garden, but avoid intentionally removing these silky insect traps.

Add Mulch and Compost

Applying mulch has so many benefits to your garden, including weed suppression, soil insulation, and moisture retention. Leaf mulch, straw, grass clippings, wood chips, and compost all provide valuable sources of organic matter for your soil while also creating a habitat where spiders can hide. 

Provide Shelter and Hiding Spots

Spiders are not sociable creatures; they like to hide and burrow when they aren’t hunting. Plant ground cover plants and leave around small piles of sticks or rocks where these eight-legged predators can hide out. These shelters provide safe areas for spiders to build webs, eat food, and lay their eggs so they can produce more pest-controlling allies.

Limit Outdoor Lighting at Night

Many spiders are nocturnal, which means they cannot do their job when it is bright outside. Avoid excessive light in your garden after the sun goes down. This is also beneficial for nocturnal predators like bats, which prey on mosquitoes and moths.

Provide a Water Source

Like pollinators and birds, spiders appreciate a little water to keep them hanging out in one area. Shallow dishes of water or a low-lying bird bath can help keep these arachnids in your garden.