Pill Bug: All You Need to Know in a Nutshell

Pill bugs, also known as sowbugs or woodlice, are small, harmless creatures often found in gardens and damp environments. They belong to the crustacean family, which means they are related to crabs and shrimp, but they’ve adapted to living on land. These fascinating creatures play an essential role in breaking down organic matter, turning decaying materials into valuable nutrients for soil and plants.

These tiny creatures have a unique appearance, characterized by their armored, segmented body and seven pairs of legs. They are nocturnal, meaning they are mostly active during the nighttime. Pill bugs don’t bite or spread diseases, making them safe to have around your garden. In fact, they can be a natural solution for breaking down waste materials and recycling nutrients in the ecosystem.

While pill bugs are generally considered beneficial to the environment, they can sometimes become a nuisance to homeowners, especially when they find their way into the house. To keep them out, make sure to eliminate any damp and decaying materials both inside and outside the home, and seal any cracks or openings that could provide entry.

Pill Bug Basics

Physical Characteristics

Pill bugs are small, usually brown or gray, crustaceans. Their body is divided into segments, with a hard exoskeleton covering their thorax. They have:

  • Seven pairs of legs
  • Two antennae
  • A pair of tail-like appendages

When threatened, pill bugs can roll into a ball to protect themselves.

Species and Distribution

There are numerous species of pill bugs, and they can be found in various environments around the world. Some common species include:

  • Armadillidium vulgare
  • Armadillidium nasatum
  • Porcellio scaber

Pill bugs are predominantly found in damp areas, such as under rocks, logs, and leaf litter. They can be found in most regions but prefer temperate climates.

Feature Armadillidium vulgare Porcellio scaber
Color Gray Brown
Habitat Damp areas Damp areas
Distribution Widespread Widespread

In summary, pill bugs are small crustaceans with various distinguishing features. They exist in multiple species and can be found in different locations worldwide, primarily in damp environments.

Habitat and Behavior

Natural Environment

Pill bugs, also known as armadillo bugs, roly-polies, and woodlice, are typically found in moist environments. They thrive in areas with high humidity, like soil, leaf litter, and under debris. These small crustaceans are related to lobsters and originate from the Mediterranean region. A few examples of common pill bug habitats include:

  • Compost piles
  • Underneath rocks
  • Foundation of buildings
  • Decaying wood
  • Forest floors, under leaves

Being nocturnal creatures, pill bugs are more active during the nighttime.

Diet and Feeding

Pill bugs primarily feed on:

  • Organic matter
  • Dead plant material
  • Decaying leaves
  • Fungi

As detritivores, they play a critical role in breaking down organic materials, contributing to nutrient cycling in the ecosystem.

Pill Bug Habitat vs Diet

Habitat Diet
Soil Organic matter
Leaf litter Dead plant material
Compost piles Decaying leaves
Foundation of buildings Fungi

Role in the Ecosystem

Benefits to Gardens

Pill bugs play a crucial role in maintaining the health of garden ecosystems. They help with:

  • Controlling pests: Pill bugs consume decaying plant matter, which reduces the habitat for harmful insects or pests.
  • Aerating soil: As these insects burrow through the soil, they help to loosen it and improve its structure, aiding plant growth.
  • Recycling nutrients: Pill bugs break down rotting vegetation, releasing essential nutrients back into the soil.

Decomposition Process

Pill bugs are primarily known for their role in the decomposition process. Here’s a brief overview of their actions:

  1. Feeding: They feed on decaying vegetation, which can include plant matter, bark, fungi, and mulch.
  2. Digestion: In the process, they break down these materials and absorb nutrients.
  3. Excretion: Pill bugs excrete nutrient-rich waste, which helps enhance soil fertility.
Activity Pill Bugs Other Decomposers (e.g., Earthworms)
Feeding on plant matter Consume decaying vegetation, bark, fungi, mulch Consume decaying plant matter, organic matter in soil
Impact on soil Aerate soil, improve structure Aerate, improve soil structure, mix organic and inorganic components
Role in nutrient cycling Break down rotting vegetation, release nutrients into soil Break down organic matter, create nutrient-rich humus in soil

Keep in mind that while pill bugs offer essential benefits to the ecosystem, they might occasionally munch on vegetables or tender young plants. Monitoring your garden and using preventative measures like creating a barrier or providing alternative food sources (e.g., decaying leaves or compost) can reduce their impact on living plants.

Pill Bugs as Pests

Damage to Gardens

Pill bugs, also known as roly-polies or sowbugs, are small arthropods that feed on decaying organic matter. Their presence in a garden can indicate moist, fertile soil, which benefits many plants. However, these creatures can also cause damage when populations grow too large. In some cases, they may feed on young seedlings, tender roots, and ripening fruits. High numbers of pill bugs in a garden may lead to:

  • Holes in delicate plant structures
  • Stunted plant growth
  • Mold growth due to excessive moisture

Pest Control Methods

Preventing a pill bug infestation is the best approach to protecting your garden. Some effective strategies include:

  • Reducing moisture by watering plants early in the day, allowing the soil to dry before evening (source)
  • Removing decaying matter from the garden area and keeping compost and mulch away from plants
  • Encouraging natural predators, such as centipedes, to live in your garden space

If you already have a pill bug infestation in your garden, you may need to consider more direct control methods. These can include:

  • Using diatomaceous earth, a natural powder that kills pill bugs by damaging their exoskeleton
  • Applying insecticides, but use caution as these can also harm beneficial insects in the garden
Pest control method Pros Cons
Diatomaceous Earth Natural, safe for humans and pets Less effective in moist areas, may need reapplication
Insecticides Effective in killing pill bugs Can also harm beneficial insects, may not be eco-friendly

When dealing with a severe infestation, it may be worth consulting a pest control professional. They can help identify the best course of action for your particular situation and ensure the pill bug population is effectively managed.

In summary, pill bugs can cause damage to gardens when present in large numbers, but proper moisture management and pest control methods can minimize their impact.

Interesting Facts and Trivia

Unique Defensive Strategies

Pill bugs, also known as roly-poly, armadillo bugs, or isopods, have a fascinating defensive mechanism. They curl into a tight ball when threatened. This not only protects their soft internal organs but also makes them less attractive to predators. Here is a comparison of their defenses with North American spiders and toads:

Organism Defensive Strategy
Pill Bug Curl into a ball
North American Spider Sting or bite
Toad Excrete toxins

Relationship with Other Organisms

Pill bugs are an essential part of their environment. They have a symbiotic relationship with a variety of organisms, including:

  • Decomposers: Pill bugs help break down organic matter like cardboard and dead plant material, making them important decomposers in their ecosystems.
  • Prey: They serve as a food source for various predators, such as spiders and toads.
  • Mother-child bond: Female pill bugs take care of their young by carrying them in a pouch, similar to marsupial mammals.

Additionally, pill bugs engage in coprophagy, which means they eat their feces. This behavior allows them to recycle nutrients and minerals, like copper, which are essential for their survival. As a result, they play a critical role in maintaining the health of their habitats.

In summary, these land crustaceans have fascinating behaviors and interactions with other organisms. Pill bugs are not only unique in their defensive strategies but also crucial in maintaining the balance of their environment, whether it’s from nibbling on carrots to engaging in coprophagy.

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 – (Not) Mating Pill Bugs

 

Mating Pill Bugs
May 22, 2010
I read online that this is rarely observed – don’t know if that’s true or not but I’m sending it to you in case you didn’t have it documented on your website. Keep up the good work.
Tim
Memphis, TN

Mating Pill Bugs

Hi Tim,
Thanks so much for contributing your wonderful images to our website.  We really appreciate the generosity of the Wildlife Theater website.  It seems strange that this would be such an uncommonly observed activity since there is no shortage of Pill Bugs in our own garden.

Update:  March 10, 2019
We just received a comment from Prigot which states:  “I’m sorry to inform you pillbug doesn’t mate in this way.. mostly for this specie able to roll in ball. Here they are having antennae contacts. The reproductive behavior is easily recognizable since male are placed on one side of the females and then on the other side. The reason is simple: females have two genital openings on the ventral side and males have two penises. So mating occurs in two stages on either side of the female. If the male is above as shown in the picture, it cannot reach the openings of the females.”  So, we are mistaken about this being mating activity.

Letter 2 – Iridovirus Infected Blue Pill Bug

 

blue sow bug
I just wanted to know if a blue sow bug is rare? Or why it is blue. I thought it was very pretty looking.
Thank you,
Melissa

Hi Melissa,
Our guess on this, and we must emphasize the guess part, is that your Pill Bug might be freshly molted and has still not darkened to gray.

Update: (04/28/2007) blue wood lice dear folks
in regard to the blue woodlouse you posted: it is infected with an iridovirus. here is a link to a page with more woodlouse information– http://www.geocities.com/CapeCanaveral/Hangar/7649/woodlice/wliceod.htm although these little blue guys are pretty–the first time i saw one, i thought it was a lapis bead and tried to pick it up; boy was i surprised when it uncurled!–they are, unfortunately, on their way to being compost. thanks for all your good bug work!
patty

Hi Patty,
Thank you so much for a most awesome update, correction and link to information.

Letter 3 – Pillbugs at the Carwash

 

Isopods in a Texas Carwash
Location:  Greenville, Texas
August 19, 2010 7:51 pm
Last year had a very dry summer here. I was helping do some repairs at a carwash and noticed a large mass of isopods hiding out in the corners of each of the wash bays. They would get blown out in the driveway when someone would wash a car, only to mosey back into the cool shadey wet wash bay after the car left!
David

Pillbugs

Hi David,
Though common names are often very descriptive and they enable the average person to remember what to call a creature since polysyllabic binomial names can often be both difficult to pronounce and difficult to remember, the use of common names can also lead to confusion, in the case of this Woodlouse.  Woodlouse is the common name indicated on BugGuide for the introduced European species
Armadillidium vulgare, which we believe is the species in your photographs.  The confusion is created in the higher taxonomy.  The order Isopoda contains the suborder Oniscidea, which are the Woodlice.  Within that suborder is the family Armadillidiidae, the Pillbugs, so named because they roll into a ball.  Children also call them Roly-Pollies.  By that reasoning, all Pillbugs are Woodlice, but not all Woodlice are Pillbugs.  The genus Armadillidium contains two species, one of them being the Woodlouse, Armadillidium vulgare.  The common name Woodlouse goes back to a more general classification after the more specific family name Pillbug has been used to differentiate those members of the order that roll into balls for protection.  BugGuide indicates the species prefers:  “Humid places under stones, bricks, or logs” so their preference for the damp corner of the carwash is quite consistent.

Pillbug

Hi Daniel,
Let me tell you how much I love your website…and how often I use it in my work as a park naturalist! A LOT!!
You forgot to mention in your reply to David in Greenville, Texas that the woodlice are not bugs/insects but crustaceans that breathe through gills, which is why they like moist, damp places. (There are also aquatic isopods!) Another cool thing about them is that the females carry their fertilized eggs in a pouch on their bodies until they hatch.  Very cool animals indeed!
Liz  (as always, please do not print my work information.  Thanks!)

Thanks for the information Liz.  Though these Woodlice were not identified as Crustaceans in our response, we did categorize them under Crustaceans.

Letter 4 – Pill Bug

 

What’s This Bug?
Hi, my girlfriend found this bug dead in our kitchen floor. Can you tell me what it is?
Thanks

This is a terrestrial arthropod known as a Pill Bug or Sow Bug. Children call them Rollie-Pollies because they roll into a ball..

Authors

    by
  • 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.

24 thoughts on “Pill Bug: All You Need to Know in a Nutshell”

  1. ummm, i’ve been doing research or pill and sow bugs latly and the reason that pillbug was blue was that it was sick not molting.

    Reply
  2. I just observed this behavior on the concrete steps outside the backdoor after a night steady light rain in northern St. Louis. They appear to be Trachelipus rathkei. Their antennae were not obvious (they have them tucked under?) and the curled under section with the pleon’s appeared to be the antennae so I was thinking this was an attack because the heads were fighting. Now that I understand what the pleon’s are it’s obviously mating. My two look nearly identical with the smaller darker shelled crustacean on top of a more mottled brown larger crustacean.

    I can tell you the process is not quick. They have been at it for 15 minutes so far. The female is moving forward and backwards in an attempt to get away. While not actually trying to throw the male off when she walks away more quickly he will sometime lose his grip a bit and then will aggressively curl under her and manipulate with his pleons and rear legs to lift her posterior off the ground.

    They are under a glass container to limit their range for she is eagerly trying to move along. I’ll reply with the final time of completion.

    Reply
  3. I just observed this behavior on the concrete steps outside the backdoor after a night steady light rain in northern St. Louis. They appear to be Trachelipus rathkei. Their antennae were not obvious (they have them tucked under?) and the curled under section with the pleon’s appeared to be the antennae so I was thinking this was an attack because the heads were fighting. Now that I understand what the pleon’s are it’s obviously mating. My two look nearly identical with the smaller darker shelled crustacean on top of a more mottled brown larger crustacean.

    I can tell you the process is not quick. They have been at it for 15 minutes so far. The female is moving forward and backwards in an attempt to get away. While not actually trying to throw the male off when she walks away more quickly he will sometime lose his grip a bit and then will aggressively curl under her and manipulate with his pleons and rear legs to lift her posterior off the ground.

    They are under a glass container to limit their range for she is eagerly trying to move along. I’ll reply with the final time of completion.

    Reply
  4. Well, the male was at it for at least 45 minutes and upon the next check-up the proved that they are powerful enough to raise up a clear quart Tubbaerware container and escape.

    Reply
  5. I really like this post. I think woodlice are amazing creatures, but a bit slow to notice they are in no danger. My question is: Is it okay for chickens to eat this bug? I love chickens and have 10. Will it affect their eggs? Will it kill them? Or will they just be okay? Please get back to me A.S.A.P., I really want to know.
    P.S. I don’t think the pill bugs will affect soil.

    Reply
    • You might want to check with folks who raise chickens. Not many predators will eat Pill Bugs, and we are not certain of the reason. We will attempt additional research into your question.

      Reply
  6. I really like this post. I think woodlice are amazing creatures, but a bit slow to notice they are in no danger. My question is: Is it okay for chickens to eat this bug? I love chickens and have 10. Will it affect their eggs? Will it kill them? Or will they just be okay? Please get back to me A.S.A.P., I really want to know.
    P.S. I don’t think the pill bugs will affect soil.

    Reply
    • Thanks for the time lapse video.

      That’s what I witnessed under my porch.

      So it’s not mating but some kind of male dominance of his preferred female?

      Could that happen with two males or females?

      The bug underneath is missing an antenna.
      I can’t tell if the bug above is feeding during the time on top.

      This maybe a method to pass beneficial bacteria between members although it seems that they may eat droppings.

      Reply
    • Thanks for the time lapse video.

      That’s what I witnessed under my porch.

      So it’s not mating but some kind of male dominance of his preferred female?

      Could that happen with two males or females?

      The bug underneath is missing an antenna.
      I can’t tell if the bug above is feeding during the time on top.

      This maybe a method to pass beneficial bacteria between members although it seems that they may eat droppings.

      Reply
  7. I know this may not be a comment related to pill bug mating but I just witnessed a pill bug or sow bug litghin up after dark it appears to be emitting a low to medium whitish light what are they doing when that happens ?

    Reply
  8. Apparently these pillbugs turn pink when you cook them as they are related to shrimp. I have them everywhere when I rake back the partially composted white and red oak leaves during the summer here in Raleigh, Nc. ( I’m moving to Uruguay, not there yet, by the way). I have heard such great things about eating bugs…the protein content, as well as lack of impact on the environment. Just a matter of the “weird” factor…..Just have to take that first step and actually try them. I have also heard that in taste tests, people liked them BETTER than shrimp. Might be neat to try!

    Reply
    • We know nothing about the edible factor of Pill Bugs, but Eat The Weeds and Eat The Planet both promote them as flavorful and healthy. David Gracer frequently comments on edible insects to our site. Based on our research, we will tag this posting with Edible Insects and we hope David Gracer can provide some personal account.

      Reply
  9. Hi everyone, I’m sorry to inform you pillbug doesn’t mate in this way.. mostly for this specie able to roll in ball. Here they are having antennae contacts. The reproductive behavior is easily recognizable since male are placed on one side of the females and then on the other side. The reason is simple: females have two genital openings on the ventral side and males have two penises. So mating occurs in two stages on either side of the female. If the male is above as shown in the picture, it cannot reach the openings of the females.

    Good continuation to all!

    Reply
  10. Hi everyone, I’m sorry to inform you pillbug doesn’t mate in this way.. mostly for this specie able to roll in ball. Here they are having antennae contacts. The reproductive behavior is easily recognizable since male are placed on one side of the females and then on the other side. The reason is simple: females have two genital openings on the ventral side and males have two penises. So mating occurs in two stages on either side of the female. If the male is above as shown in the picture, it cannot reach the openings of the females.

    Good continuation to all!

    Reply
  11. I just saw a pill bug crawl on top of another. The bottom one immediately rolled up while the other moved around on top for over 5 minutes (my toddler got bored so we left). Was this an attack? Sorry no pictures!

    Reply
  12. This is mate guarding behavior. For some time after mating, males will sit on top of/crawl over females for protection.

    Reply

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