What Do Woodlice Eat? Unveiling Their Mysterious Diet

Woodlice are fascinating creatures often found in damp, dark environments, like beneath rocks and logs in gardens. Also known as pill bugs or roly-polies, these little critters play a significant role in the ecosystem, but what exactly do they eat?

Primarily detritivorous, woodlice thrive on a diet consisting of decaying organic material. Their menu includes leaf litter, rotting wood, fungi, and bacteria which are essential for nutrient cycling in soil ecosystems. As they munch through these decomposing materials, woodlice help break them down into simpler compounds that plants can use for growth.

However, woodlice aren’t picky and can adapt their diets depending on what’s available in their habitats. Although they favor decaying matter, they may also consume fresh plant material and algae. So, next time you come across these tiny isopods, rest assured that they’re putting in the work to maintain the health of your garden and soil.

Understanding Woodlice

Biology of Woodlice

Woodlice are small terrestrial crustaceans that play a crucial role in recycling nutrients as they feed on decaying plant material. They have a hard exoskeleton, which is typically grey or brown in color, providing protection for their body. As arthropods, woodlice have multiple pairs of legs that help them move around efficiently in their habitats, mainly leaf litter, decayed wood, fungi, and bacteria.

These little recyclers are essential for maintaining the health of ecosystems, especially in soil dynamics. They belong to the order Isopoda, comprising various species like Armadillidium, Oniscus, and Porcellio. Some common names for woodlice include pill bugs and sow bugs, which might give you an idea about their appearance.

Types of Woodlice

There are many species of woodlice, but let’s focus on a few common ones:

  • Grey Woodlouse (Oniscus asellus): This species has a light grey color and can thrive in a wide range of habitats.
  • Common Pill Bug (Armadillidium vulgare): They are known for their ability to roll up into a ball for protection, giving them the name “pill bug.”
  • Common Sow Bug (Porcellio scaber): Unlike pill bugs, the sow bugs can’t roll up but have a flatter, semi-flexible exoskeleton.

Now, let’s take a closer look at their characteristics:

Species Color Habitat Special Feature
Grey Woodlouse Light Grey Wide range Adaptable
Common Pill Bug Brown Diverse areas Rolls up into a ball
Common Sow Bug Dark Grey/Black Various habitats Flatter, flexible body

In conclusion, understanding the biology and types of woodlice will give you a better insight into their role as recyclers and the variety of species that exist in the world. With this knowledge, you can appreciate their importance in maintaining the health of diverse ecosystems.

Diet of Woodlice

Natural Diet

Woodlice are detritivores, which means they primarily feed on decaying plant material, such as leaves, logs, and other debris found in damp environments. In addition, they consume organic matter like fungi, helping to break down these substances and contribute to a healthy ecosystem. For example, in your compost heap, you might notice an abundance of woodlice aiding in the decomposition process, turning rot and decay into nutrient-rich compost.

A typical woodlice diet also includes the exoskeletons of other woodlice, which are shed regularly as they grow. This process of eating their own exoskeleton provides essential nutrients and helps maintain their habitat’s moisture levels. In this way, woodlice play a vital role in nutrient cycling within ecosystems.

Unusual Food Preferences

Although decaying plant material forms the basis of their diet, woodlice have been known to occasionally consume other substances, such as paper or even human skin cells. However, these instances are relatively rare and generally do not result in infestations or damage to your property.

In damp environments, they may also nibble on materials like clothing or carpets, particularly if these items have come into contact with rot or decay. To minimize any potential interaction with woodlice, ensure that your home has adequate ventilation, promptly remove damp or decaying materials, and maintain a clean and dry living space.

As detritivores, woodlice are essential members of ecosystems, helping to break down organic matter and recycle nutrients. However, their unusual dietary preferences can sometimes lead to unexpected interactions with humans. By understanding their natural diet, you can take steps to create a comfortable balance between these fascinating creatures and your own living environment.

Woodlice’s Role in the Ecosystem

Cleaning and Recycling

Woodlice are small crustaceans that play a vital role in the ecosystem. As detritivores, they consume decomposing plant material and organic matter on the ground. By doing so, woodlice help recycle nutrients back into the soil, promoting plant growth in their habitat. Here are some examples of what woodlice eat:

  • Decaying leaves
  • Rotting wood
  • Dead plant material

In addition, woodlice help keep the ecosystem clean by breaking down organic matter into smaller pieces that other decomposers can process. They also aerate the soil as they move, which helps maintain soil quality.

Prey in the Food Chain

Woodlice not only help maintain a clean ecosystem, but they also serve as an essential food source for various predators. Ground beetles, centipedes, spiders, and even toads are among the many animals that rely on woodlice as a crucial part of their diets. As prey, woodlice contribute to the overall balance and stability of their ecosystems, making them essential links in the food chain.

Food Source Predator
Woodlice Ground Beetles
Woodlice Centipedes
Woodlice Spiders
Woodlice Toads

Remember, woodlice infestations in your home are highly unlikely, as they prefer outdoor habitats with plenty of organic matter to consume. They pose minimal risks to humans and pets and should be appreciated for their vital role as recyclers and contributors to a healthy ecosystem.

Woodlice and Homes

Effect on Homes and Gardens

Woodlice thrive in damp environments and are commonly found in gardens, logs, and compost heaps. Although they are harmless to humans, woodlice can sometimes be considered pests when they enter homes. In your garden, they could munch on seedlings and tender plant parts.

In your home, they’re usually attracted to poorly ventilated and damp areas like basements. Woodlice can potentially cause damage to wooden furniture, stored cardboard, or paper products. However, it’s important to note that the presence of woodlice can also be an indicator of underlying dampness or moisture issues in your home.

Control and Management

Managing a woodlice infestation in your home and garden mainly involves reducing damp conditions and sealing entry points. Here are some effective ways to control and manage woodlice:

  • Ventilate: Ensure your home is well-ventilated, especially in damp-prone areas like basements.
  • Fix Moisture Issues: Repair leaks, use dehumidifiers, and fix any moisture problems in your home to make it less attractive to woodlice.
  • Seal Entry Points: Seal gaps, cracks, and other potential entry points around your home where woodlice could enter.
  • Keep Gardens Clean: Regularly remove decaying plant material, and properly store firewood to reduce woodlice habitat in your garden.

When it comes to woodlice control, using chemical pesticides should be a last resort. In most cases, you can manage infestations using a vacuum cleaner to remove them from your home and by making necessary adjustments to your home’s environment. Proper home and garden maintenance can help prevent future woodlice issues.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Woodlouse


Location: scarborough, Ontario, Canada
December 15, 2013 2:40 pm
Hi guys!!
Okay so I moved into a new basement apartment yesterday (its December and quite cold) When I first walked in I saw about 4 of these bugs dead in a small spider web. so I just cleaned it up and thought of nothing since the apartment had been vacant for about a month. Then last night I saw about 4 more of these bugs walking. I killed them. I didn’t see any this morning, but then after I had breakfast I saw 3 more in the bedroom. One of which was crawling out from under the baseboard. I need to know what this is. Im afraid I have an infestation and I just moved in. I don’t know what this is though. I hope you can help.
Signature: Tania


Hi Tania,
This is a Woodlouse, and we believe we have correctly identified it as
 Porcellio spinicornis thanks to photos posted to BugGuide.  According to BugGuide, these Woodlice are found:  “wherever cool, dark, moist places are available to shelter woodlice from dryness and heat during the day.”  Your basement apartment fits that description.  Woodlice are benign and they will not harm you, your pets, your apartment or its furnishings.  They may be a nuisance if they are plentiful, but they are basically benign creatures.

Letter 2 – Woodlice in Operating Theater in India


Subject:  Identify insect
Geographic location of the bug:  Hyderabad
Date: 12/14/2018
Time: 12:18 AM EDT
Your letter to the bugman:  Hello sir,
Plz tell us the source of this bug
We work at hospital., These bigs are found in operatiom theatre.Which is not at all acceptable..
We would like to know, what kind of bugs are these and why they reside in OT..
Source of these bugs..
Kindly help us.. as soon as possible.
Thank you
How you want your letter signed:  Mail


These are terrestrial Isopods known as Woodlice or Sow Bugs, and they are benign.  They are generally found in moist environments where they feed on decaying organic matter.  Though it is a North American identification site, the information on BugGuide is relevant.  According to BugGuide the habitat is “wherever cool, dark, moist places are available to shelter woodlice from dryness and heat during the day” and their food includes “Plant material, usually dead. If live plants are soft and moist enough on the outside, they will eat them and sometimes do damage.”  Is your operating theater on the ground floor or below ground in a basement?  They are likely entering through cracks and spaces in the walls, so sealing off the operating theater from the outside environment should remedy the matter.

Hello sir..
Our operation theatre is located in 3rd floor above the ground..
And we noticed these bugs in OT after a rainy day…
Thank you for your valuable time..
I will revert back to you , when necessary…

Letter 3 – Woodlouse


Subject: What is this
Location: Ottawa, Ontario, Canada
April 24, 2014 5:57 am
Just want to identify this bug
Signature: Jesse Larocque


Hi Jesse,
This is a Woodlouse or Sowbug, a type of terrestrial Isopod.  Though they often enter homes, they are considered benign and they will not damage your house or its belongings, unless rotting organic matter is valuable to you because that is what they eat.

Letter 4 – Woodlouse


Subject: Bug
Location: Bronx, New York
December 11, 2016 7:57 pm
I found this bug crawling on the floor in my room. What kind of bug is this? I live in an apartment building.
Signature: What letter?


This is a Woodlouse in the Suborder Oniscidea, and according to BugGuide, they are found:  “wherever cool, dark, moist places are available to shelter woodlice from dryness and heat during the day.”  They are generally found outdoors, or in basements, so we are guessing you are in a ground floor apartment.

Letter 5 – Woodlouse


Subject: Creepy crawler every summer
Location: Miami, Florida
April 24, 2017 8:40 pm
Every summer I get these in my room. I have a wall a.c. unit. I always think this is the way they get in but then I find them coming out from under my bed. I live in Florida. I thought I got rid of them but I guess it was the cooler months. I need help.
Signature: Stephanie


Dear Stephanie,
This is a Woodlouse and they like damp conditions.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

1 thought on “What Do Woodlice Eat? Unveiling Their Mysterious Diet”

  1. I have haas several random small bugs just like this. 2 times in my car. One time in my house. crawling on a towel or my clothing. Very small. Black. Almost like a weevil. I am also in florida.


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