How are Spiders Beneficial in Pest Control? What Do Spiders Eat?

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Last update: 03.08.2020

Spiders are not a pleasant sight to see at home, however, something not many people appreciate is the fact that spiders can often be described as nature’s pest control. In recent years it’s been growing popularity in leaving house spiders to live rent-free in houses and gardens.

People realised that spiders aren’t dangerous to humans, pets, or produce but quite the opposite in fact. Spiders can be natural pest control against terrorising insects.

What Do Spiders Eat?

Spiders are at the top of the food chain in the insect world. They’re not exactly insects but are classified as arachnids. Often, but not necessarily, spiders hang out near water sources, like your bathroom, because their prey is attracted to water.

Spider Diet

Their diet includes basically any insect that flies or crawls, including ants, bees, mosquitoes, cockroaches, centipedes, aphids, flies, beetles. However, there are some exotic species (not native to the UK) that also feed on scorpions, even sometimes small vertebrates, such as frogs and bats.

Most common house spiders in the UK are predators and will control the population of other insects inside your home. They capture and eat live prey or recently deceased in their webs. 

Do Spiders Eat Woodlice?

Woodlice tend to inhabit moist places both in your home garden. While not all spider species would eat these creatures, there is one species that feeds primarily on woodlice. It’s the Woodlouse spider. 

Do Spiders Eat Fleas?

Yes, whether the fleas are in your garden or inside your house, spiders will happily feed on them. Keep in mind that if you have a heavy flea infestation, spiders alone cannot take care of the problem. 

Do Spiders Eat Silverfish?

Yes, some species are known predators of silverfish. Most commonly the spitting spider includes them in their diet. In case a silverfish infestation is brewing somewhere in your home (most often in basements or attics), the presence of spiders can help prevent it in the beginning. But as with any other heavy infestation, spiders won’t be able to handle it on their own. 

Do Spiders Eat Bed Bugs? 

If the spiders are big enough they could eat bed bugs. Since bed bugs mostly stay near the bed but spiders do not it’s not that often that they cross paths. However, spiders will not eat enough of them to control their population. So if you have a bed bug infestation, you must contact bed bug control specialists.

Do Spiders Eat Other Spiders?

Some species can prey on their own kind if food is scarce. An example of a species turning to cannibalism is the Pholcus phalangioides, aka Daddy long-legs. No spider species actively seek other individuals to eat them as part of their diet. 

Furthermore, there is reproductive cannibalism in the spider kingdom. It is common in the insect world and often it’s the females which kill and eat the males after copulation. If there are cases in which males eat females, they are extremely rare.

Check also:

What attracts spiders?

Spider bites.

So, Why Do Spiders Invade My Home?

It is a common misconception that spider invasions increase in Autumn because they are looking for shelter for the winter. However, this isn’t conclusively proven. 

They usually make their home in people’s houses to hide from the harsh elements outside. Once they have found a warm cosy place, they would wait for any other unwelcome insect, like a mosquito, for example, to fly by their web.

If there is no food around, they would find another place to live. Still, it’s not pleasant to have them at home, and if their population goes out of hand, you might need to give a call to a spider control professional.

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How Effective are Spiders in Pest Control?

In a word – very effective. The world’s estimated 25 million metric tons of spiders eat between 300 and 800 million metric tons of food per year. This means that on average, a single spider eats about 25 metric tons of food each year. This food mostly consists of insects, small vertebrates and a small part of it is also plant matter.

This means that leaving a couple of house webbing spiders means they will take care of any other type of insect that happens to enter your home. The same goes for leaving spiders in your garden. If you see a spide’s nest do not be quick to destroy it. Leave them be and they will protect your flowers and produce from destructive pests, such as aphids.

How to Make Spiders Useful in my Garden?

After learning this mind-numbingly large number of food they eat, the first thing one would think about is how to put these hungry little creatures to good use? The best idea you can have is, unleash them in your garden.

There are already stores where you can buy spiders and praying mantis (the other insect predator) to use as a biological weapon against all those pests who eat your garden plants. The good thing about spiders is that only a few species are known to eat plant matter, so as long as you don’t get any of those, you’ll be fine.

Now, you won’t need to spray your garden with any harmful insecticide.

An elegant idea like this is unfortunately not as widely spread as it should be since people are squeamish when it comes to having to deal with insects of any kind. This huge number we mentioned earlier is measured mostly in forests and mountains where the spiders play an important role in keeping the insect populations under control.

But, utilizing them for personal use can only work for the better.

Check also:

Do You Really Swallow Spiders in Your Sleep?

UK Spiders – Dangerous or Beautiful?

Is there a Con of Using Spiders in the Garden

One of the problems you may encounter is that spiders are relatively likely to also attack other spiders since they can get aggressively territorial. This might reduce the beneficial insects in your garden. However, so far it never was regarded as the kind of drop that would increase the population of the harmful insects.

When you introduce a predator to an environment with lots of food, it’s normal that they grow in population, and eventually, they will have to compete. It’s all part of evolution.

Another con can be that if their population grows out of control they may also get inside of your house and then you may need to get professional pest treatment.


Spiders can be a very effective form of insect control if you have a flower or food garden. They would kill all unwanted pests while preserving your plants and even decorating them with beautiful shiny webs. Do you agree with us? What other tips and tricks do you know about biological pest control? We’d love it if you share them below in the comments.

Picture source: prdyapim /

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One Response

  1. Rob says:

    On average, a single spider eats about 25 metric tons of food each year… seriously? That’s a lol! Nice post, thanks for sharing!

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