Woodlice: All You Need to Know – A Friendly Guide

Woodlice are fascinating little creatures that play an important role in the natural decay process in various ecosystems. Often found in damp and dark habitats, these crustaceans break down organic matter, contributing to a healthier environment for your gardens and other green spaces.

As part of the isopod species, woodlice have unique characteristics that set them apart from other common garden inhabitants. They typically thrive in moist areas, as their bodies require a certain level of humidity to survive. This makes them highly beneficial to ecosystems where decomposition occurs, such as in leaf litter and on decaying wood.

Given the multitude of woodlice species found worldwide, it’s worth exploring and understanding their habits to appreciate their contributions to the environment. So next time you see these little isopods in your garden, remember they’re hard at work maintaining the ecological balance of their habitat.

Woodlice Biology and Identification

Species and Common Names

Woodlice are fascinating creatures with over 3,000 species worldwide. Some common species you might come across are Oniscus asellus and Porcellio scaber. They go by various names such as pill bug, slater, armadillo bug, and roly-poly.

Physical Characteristics

Woodlice have a distinct appearance with their segmented exoskeleton that is usually brown or grey in color. Some key characteristics to help you identify woodlice:

• 14 legs
• Sections called plates on their body
• Curved, oval-shaped body

Reproduction and Life Cycle

Woodlice undergo interesting reproductive processes. Females carry eggs in a special pouch called a marsupium. After hatching, young woodlice emerge as a manca, which resembles a smaller version of the adults. Some important aspects of their life cycle:

• Females can store sperm for months
• Reproduction occurs mostly in spring and autumn
• Woodlice continue to molt even as adults

Ecological Role and Behavior

Woodlice play a crucial role in ecosystems by breaking down organic matter and returning nutrients to the soil. They prefer damp and dark habitats like forests, leaf litter, and under stones. Some of their notable behaviors include:

• Detritivores, feeding on decaying plants and animals
• Nocturnal creatures
• Rolling into a ball when threatened

Now that you have a better understanding of the biology, identification, and ecological significance of woodlice, you can appreciate these fascinating creatures and their contributions to our environment.

Woodlice in the Home and Garden

The Issue with Woodlice Infestation

Woodlice are common pests found in homes and gardens. They may not be harmful to humans or pets, but their presence could indicate an infestation of other pests like ants. In large numbers, woodlice can damage wallpaper and wooden structures due to their preference for damp and decaying environments.

Environment Favoring Woodlice

Woodlice thrive in moist, dark, and organic environments. They are commonly found around damp soil, rotting wood, and in compost piles. Factors that attract woodlice to your home or garden may include:

• Dark and humid spaces
• Leaking pipes
• Poor ventilation

To prevent a woodlice infestation, it’s essential to address these factors by improving your home’s ventilation, fixing leaks, and clearing out damp areas.

What Do Woodlice Eat?

Woodlice feed on decaying organic matter. In your garden, they are likely to be found near leaves, logs, dead plant material, and rotting wood. Here’s a brief list of common woodlice food sources:

• Leaves
• Logs
• Decaying plant matter
• Compost piles
• Rotting wood

While woodlice can help in breaking down organic matter and contributing to a healthy ecosystem, their population should be controlled to maintain a balance in your home and garden.

Controlling and Preventing Woodlice Infestations

Natural Predators of Woodlice

Woodlice have several natural predators that keep their population in check. Some examples include:

• Ants
• Spiders
• Centipedes

Introducing or encouraging these predators into your garden can help maintain a balance and prevent woodlice infestations.

Human Control Methods

When dealing with a woodlice infestation, you can use various control methods:

• Diatomaceous earth: Sprinkle it around affected areas to deter woodlice. This natural remedy works by damaging their exoskeleton and causing dehydration.
• Insecticides: Choose a chemical control suitable for woodlice, but always follow the instructions and safety measures on the label.

Preventative Measures

To prevent woodlice from becoming a problem in your home or garden, try these tips:

• Ventilation: Ensure proper airflow in damp and dark areas to discourage woodlice from settling.
• Remove decay: Regularly clean up leaf litter, rotting wood, or other organic debris that can attract woodlice.

Questions and Answers

Q: Can woodlice infest my home?

A: Although primarily found outdoors, woodlice can enter your home if there is a damp or decaying environment for them to thrive in.

Q: Are woodlice dangerous?

A: No, they don’t carry diseases or cause any significant damage to your home. However, large numbers can be a sign of damp or decay issues that you should address.

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 – Orange Woodlouse

Subject: Bright Orange Woodlouse
Location: Missouri, United States
March 20, 2015 11:49 am
during my searches for various bugs and critters I’ve come across a total of three of these bright orange woodlice. I have a large plastic tub full of woodlice that I feed and observe, so the three I’ve found are part of my little ecosystem now.
what I’m wondering is, is this a rare genetic coloration of some sort? or a different species of woodlouse than the gray ones? perhaps neither and it’s something else, so I thought I’d ask you!
Signature: Stolz

Dear Stolz,
Long ago we fielded a question about a Blue Sowbug and we learned it was infected with an Iridovirus which caused the coloration.  We found a similar question posted to BugGuide, but there is no response other than that it is identified as the European Sowbug, Oniscus asellus.  On the Woodlice Oddities Page, it states:  “Orange Porcellio scaber This orange form appears to be rare in this region. The example here is the only one found in a collection of over 400 from the same compost heap – it is also the only one, of two, that I have observed over the last 10 years. The red forms of woodlice are genetically determined but their rarity suggests that this form is not as well adapted to the habitat as the darker gray forms.”  On Terrain.net it states:  “The Orange woodlice is a rare colour form the the common slater  Porcellio scaber.”  On BugGuide we learned that Porcellio scaber is a synonym for Oniscus granulatus.

Letter 2 – Woodlice found in home brewery

Subject: What’s this bug?
Location: Drumheller, Alberta, Canada
February 10, 2013 8:43 pm
This bug was in the basement where I home brew my own beer. There is a lot of grain sitting around but all in sealed containers. Just wondering what kind of bug this is?
Signature: Neil

Hi Neil,
This Woodlouse and its relatives were probably living in your basement long before it became a home brewery, but you probably didn’t notice them because you didn’t spend as much time there before.  Woodlice are terrestrial Isopods that are classified as Crustaceans.  According to BugGuide:  “Woodlice need organic matter, which can be found in most soils, and they need cool moist conditions. Many places that might seem too hot and dry have cool hiding places where they can wait out the dryness and heat. Woodlice hide during the day anywhere cool and dark, so they’re easily when the items they hide in are moved. They can be found anywhere humans live and cool, moist conditions exist.”  BugGuide also notes that they eat:  “Plant material, usually dead. If live plants are soft and moist enough on the outside, they will eat them and sometimes do damage.”  Woodlice are also known as Pill Bugs and Rollie Pollies.

Letter 3 – Rollie-Pollies or Woodlice

Subject: Rollie Pollies
Location: Caldwell, Idaho
October 29, 2012 7:51 pm
Dear Bugman,
I’m doing a bug collection for school, What is the scientific name for Rollie Pollies?
Signature: Kaesha

Dear Kaesha,
Your photos are so nice.  We wish they were of higher resolution.  Rollie-Pollie is a common name used for Woodlice or Pill Bugs, Crustaceans in the suborder Oniscidea.  You can see the taxonomy breakdown on Bugguide.

Ed. Note: We did a bit more research and as we suspected, these images were pilfered from the internet.  Our submission form contains a disclaimer:  “Also, you swear that you either took the photo(s) yourself or have explicit permission from the photographer or copyright holder to use the image.” We will be writing to the author of The Sweeting Spot to request permission to reproduce the photograph.  Plagiarism is an issue that we take very seriously.

Erika from The Sweeting Spot responds
Subject: Re: Rollie Pollie photo
Website: The Sweeting Spot
October 30, 2012 10:17 am
I received a message from Daniel a few moments ago about photo usage for a rollie pollie photo that I used on my personal blog a few years ago. I’m a bit embarrassed to say that I don’t own the photo – I thought I got it from a free stock photo website, but I could be wrong. It’s possible I may need to take it down as well! Sorry I couldn’t be more help.
Signature: Erika

Thanks Erica,
We looked at the metadata in the digital file and it does not exist.  I think we are both safe at this point.

Letter 4 – Woodlice

Subject: Identify bug
Location: Davidson
November 12, 2016 11:25 am
Hi we would like to know what type of bug my son had in his basement bathroom. Seems to come from under the corner shower.
Thanks
Signature: Flo

Dear Flo,
These are Woodlice or Sowbugs, and children commonly call them Rollie-Pollies because they curl into balls.  They are harmless, and though they are normally found outdoors in the garden, they can sometimes be found in damp areas indoors.  Where is Davidson?

Hi,
Thanks for the response.  Davidson is between Saskatoon Saskatchewan and Regina Saskatchewan (about half way).
Is there anything we can use to get rid of them?
Thanks again,
Florence

Thanks for the clarification.  We do not provide extermination advice.

Letter 5 – Rollie Pollies

Dear Bugman,
What is the scientific name for rollie pollies and what do they eat? Are the on the website?
Thanks. Mom Adams

Dear Mom Adams,
We just got a question about Pill Bugs or Sow Bugs, which are Isopods, not true insects. The common Pill Bug goes by the scientific name Armadillidium vulgare. They are omniverous and eat young and decaying plant material. We had not heard of the common name Rollie Pollie until our student Betina mentioned it. Thank you for reaffirming that local term.

Letter 6 – Woodlice

Subject: Tree infestation
Location: Los Angeles, California
April 21, 2014 9:12 am
I have an infestation in a mature (about 50ft high) Camphor tree. The infestation seems to be around the root and the insects (in the picture) are revealed if I pull some bark out. Any help identifying the insects would be appreciated, thanks.
Signature: Anshuman Prasad

Dear Anshuman,
These are Woodlice, a type of terrestrial isopod.  They are commonly found in cool, dark, damp places within the garden where they feed on dead plant material.  If the base of the tree is rotting, they may be feeding on the rotting wood, but they will not harm living portions of your camphor tree.  Woodlice will also enter homes, and they are most frequently found in basements where the conditions are favorable.