Research Rolypolies

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April 2003, p. 43-44

The Home Zone

Research Rolypolies

Kathleen Damante

April is a good time to go outdoors and examine living things. Pill bugs are good to study because they are easy to find and care for and do not bite. You might know these organisms by one of their nicknames�potato bugs, wood lice, and rolypolies. Whatever you call them, you and your family can learn about these interesting creatures and have fun examining specimens up close.

Pill bugs have flattened oval bodies with no wings and are usually brown or gray. They have seven pairs of legs and overlapping "armored" plates that make them look like little armadillos. Pill bug is the common name used for both pill bugs and a very similar type of bug called a sow bug. Sow bugs differ from pill bugs because they have two tail-like structures on the back. Pill bugs do not have these tail-like structures and can roll up into a tight ball to protect themselves. This is how they originally got their name because people thought they looked like pills when they rolled up.

Surprisingly, pill bugs are not insects. Insects have hard outer skeletons (exoskeletons) and three pairs of legs. Pill bugs actually belong to the same class of animals as crabs and shrimp. This class of animals called crustaceans has exoskeletons, antennae, and many pairs of jointed legs. Pill bugs belong to a special group of crustaceans called isopods. Isopod means "equal foot." Unlike crabs and lobsters, an isopod�s legs are all the same shape. Most crustaceans live in water but pill bugs live on land.

Habits and Habitat

Pill bugs breathe through gill-like structures and must live in moist places. They are usually found underneath things that provide darkness and moisture, such as rocks, piles of decaying leaves, and tree bark. In their natural habitat, pill bugs generally eat decaying wood, leaves, and other vegetation. Pill bugs are cold blooded. Their body temperature depends on the temperature of their surroundings.

Caring for Pill Bugs

Search for pill bugs under flat rocks and piles of rotted leaves. Try looking underneath the stripped away bark of dead trees or other places where it is dark and damp.

Make a habitat for pill bugs in a plastic container with a few holes in the top for ventilation. Put in dirt, sticks, and some decaying matter such as leaves, bark, etc. Place a wet paper towel in the container to keep it moist and add pieces of potato for the pill bugs to eat. Keep the container in a slightly dark place. Use the pill bugs you find to complete the activities below.

Kathleen Damonte is a middle school science teacher in the Montgomery County Public School System in Maryland.

NSTA Connection

More great pill bug activities for students can be found in the book The Pillbug Project: A Guide to Investigation. To read a review of this book, click here.

Pill Bug Party

Pill Bug or Sow Bug?

Materials:

One piece of white paper
Two or more pill bugs
Magnifying glass or hand lens (optional)
Plastic container (containers from a grocery store salad bar work well)
Permanent marker
One paper towel cut in half

Directions:
1. Put two pill bugs on the paper. Observe them carefully. Use the magnifying glass if you have one.
2. Touch the pill bugs gently with the tip of your finger or the eraser end of a pencil.

Draw one of the pill bugs in each of the boxes below. Include as many details as possible.

Questions
1. Compare your two pill bugs. How are they alike and different?
2. Determine whether each one is a pill bug or a sow bug. How do you know?

Moist or Dry?

Directions:
1. Draw a line with the marker down the center of the plastic container.
2. Fold the pieces of paper towel in quarters. Dampen one half and place it on one side of the container. Place the dry one on the other side.
3. Place at least two pill bugs (more if you have them) on the line in the center and let the container sit undisturbed for two minutes.
4. After two minutes, count how many pill bugs are on the moist side and on the dry side.

Record your data on the table. Repeat two more times. Find the mean (average) of your data.

Questions
1. According to your data, did the pill bugs prefer a moist or a dry environment?
2. Design an investigation and find out whether pill bugs prefer a dark or a light environment.

When you are done investigating, be sure to release the pill bugs back into their natural habitat. Also, don�t forget to wash your hands!

Click here for PDF file.