What to Know About Pill Bugs

Medically Reviewed by Poonam Sachdev on January 03, 2023
Written by Alyssa Anderson
5 min read

Pill bugs are common but unique creatures that are found throughout the world, including the U.S. They’re also known as rolly pollies because of their tendency to curl up into a ball when they’re threatened. 

Pill bugs occasionally become household pests. But, for the most part, they’re good for the environment and are fascinating research subjects in both classroom and laboratory settings.

At first glance, many people think that pill bugs are a type of insect. In fact, they’re one of the few crustacean species that have evolved to live on land. Examples of their aquatic relatives include: 

  • Shrimps
  • Crabs
  • Lobsters

All species of pill bugs originated in the Mediterranean region. Human activity spread them to all inhabited lands. Today, many different species of pill bugs exist around the world. In the U.S., the most common species is Armadillidium vulgare.

To protect themselves, these rolly pollies will curl into a tight ball when they experience any kind of startling sensation — from a sharp poke to significant vibrations.

The average pill bug size is quite small. They’re oval in shape and are longer than they are wide. They range in length from about one-quarter of an inch to five-eighths of an inch. Males and females are about the same size. 

Pill bugs have 14 legs in seven pairs. They also have small heads and abdomens. Their thoraxes are divided up into seven overlapping plates. This gives them a distinct armored look. This jointed thorax gives them the flexibility that they need to curl up in a ball and protect their more vulnerable undersides.

They range in color from brownish to grayish black.

Pill bugs like to live in moist, shady environments. They often bury themselves several inches below the ground to avoid the heat and drying air. You can commonly find them under all kinds of decaying vegetation and in the cooler parts of compost piles. 

They enjoy living in gardens, greenhouses, and around the edges of buildings. They can sometimes become pests in these environments when there are too many of them around.

Pill bugs don’t bite and don’t spread any human diseases. As a species, they cause minimal crop damage and are relatively easy to manage. 

Plus, they help recycle decaying matter back into the environment, and their activities stimulate soil bacteria. This has an overall positive impact on soil quality. 

The main way that pill bugs become pests is during seasons when there are far too many of them around — like years with a lot of rain. Normally, pill bugs eat decaying vegetation, seeds, and dung. But in these situations, they start to eat small, vulnerable flowers and vegetables. New transplants are some of their favorites. 

In extreme cases, they can devour an entire young plant to the ground in the span of a single night. Some of the plants that they like to munch on include: 

  • Hostas
  • Primroses 
  • Pansies 
  • Alyssums
  • Certain daisies
  • Dahlias 
  • Zinnias
  • Garden vegetables — particularly ones with fruit that rests on the ground

You’ll need to find ways to eliminate your pill bug communities if you find that they’ve started to nibble on your garden plants. 

In a classroom setting, students can use pill bugs to learn about a variety of important biological topics, from the web of life to the unique behaviors of small creatures. And they’re easy to maintain in a laboratory environment. 

These crustaceans are even safe to eat. People say that they have a slightly salty taste and a crunchy texture. Unless they become plentiful enough to be a problem, they’re not bad creatures to have around.

If you ever see a pill bug wandering around inside of your house, then you likely have a huge population thriving somewhere outside. The main way to deal with your pill bug problem is to get rid of all of the places for them to hide and reproduce. For the most part, this means getting rid of as many cool, moist environments as you can. 

To disrupt their outdoor communities, you can: 

  • Remove all extra leaf litter, mulch, and grass clippings from your lawn
  • Elevate all objects that would otherwise permanently rest on the ground — this includes things like pots, planters, dog houses, and piles of wood and stones
  • Adjust the drainage system around the outside of your house so the soil has time to dry out between rains or watering sessions
  • Use pesticide sprays or bait traps outdoors — just make sure to carefully read and follow all of the instructions on any pesticide because many of them are dangerous when you don’t use them correctly

If the insects are starting to get inside, there are a few more steps that you can take. These include: 

  • Sealing the edges of your doors and any cracks in your foundation to prevent their entry
  • Vacuuming them up — or simply picking them up by hand — once they’ve gotten in
  • Eliminating perpetually damp spots in your basement, attic, or crawl space 
  • Calling a professional pest control service if the situation becomes unmanageable or long-lasting

In some cases, you might be trying to raise pill bugs, not kill them. You may want to keep them for science experiments, as learning models, or simply as pets. In these cases, you’re in luck — pill bugs are simple to both find and maintain. 

To get your pill bugs, you can likely go out and find them in the moist regions of your own backyard. Lift up pots and rocks or dig around at the edges of your flower beds to find your samples. They’re harmless, so it’s safe to simply scoop them up and add them to a functional tank or terrarium. 

Pill bugs survive best in community settings, so it’s best to get more than one individual. This way, they can also reproduce and form a sustainable community within your provided environment. 

In laboratory settings, they’ve survived well when provided with: 

  • Fluorescent lights for between six and 10 hours a day
  • A temperature range of 68°F to 77°F
  • Plenty of leaf litter and other types of cover
  • Moist soil — with some regions reaching 100% humidity

Pill bugs are pretty interesting creatures. They resemble their aquatic relatives in a lot of ways but have evolved a number of unique behaviors to help them survive on dry land. Some interesting pill bug facts are listed below: 

  • The mothers carry their eggs in brooding pouches on the underside of their bodies. Small, young pill bugs emerge after developing for 45 days. 
  • Thanks to their underwater origins, a pill bug’s biggest problem is maintaining water in their bodies. They can go up to three months without food but can’t last longer than two days in dry environments. 
  • Pill bugs usually live for about two years.
  • For most species, both male and female pill bugs reach sexual maturity — and can begin reproducing — when they’re a year old.

The next time you’re puttering around your garden or strolling through the woods, keep an eye out for these bizarre land crustaceans. You may find that they’re more interesting than they first appear.