Science project

Sow Bug and Pill Bug Behavior


  • 6+ sow bugs and pill bugs
  • Small plastic terrarium with lid
  • 1 ft. black poster board
  • Tape
  • Half of a peeled potato
  • A 2-inch square piece of sponge
  • 1/4 cup wet leaves
  • 4 cups organic potting soil
  • Spray bottle


  1. Create a habitat for your bugs. Put 4 cups of organic potting soil in a terrarium.
  2. Add ¼ cup wet leaves to one corner, a 2-inch square piece of sponge in another, and half a peeled potato in another.
  3. Surround the habitat with a foot of flexible black poster board on the outside. The cardboard will keep things dark in there.
  4. Next, you will need to find some sow bugs and pill bugs. How can you tell the difference? Sow bugs have a feathery appearance on their sides, while pill bugs look smoother and more rounded. When you pick up a pill bug, it may roll into a ball. Look under plants, rocks, and wood in the garden. If you can’t find any sow or pill bugs, put some old pieces of wood in the garden, wait for a week, and then look underneath.
  5. Once you have your bugs, place them in their habitat. Let them get used to their new home for a day. Now, you’re ready to experiment!
  6. Remove the black piece of paper from around the terrarium. Look in the terrarium for sow bugs and pill bugs. What are they doing? Look under the wet leaves, the potato, and the sponge. Are there any bugs under there? How many of each kind are in each habitat?
  7. Move the container very gently back and forth. What happens now?
  8. Pick up one of each type of bug. What do they do when you pick them up?
  9. After a few days, take a look at the potato and the leaves. Do you notice any changes?


Both sow bugs and pill bugs seek out damp places with rotting vegetation. Pill bugs roll into a ball when they are scared.


Sow bugs and pill bugs are amazing little creatures. They’re crustaceans like crabs, but you can often find them in your garden. They are also called isopods. All of these roly-poly crustaceans are in the scientific order Isopoda. Isopods actually breathe through gills. Since they don’t live underwater, they need to find wet places where they can keep their gills damp.

Sow bugs and pill bugs eat rotting plants. They have a fairly broad diet, and they live in their food, which means that you’ll often find them munching on damp, rotten plants. They make little holes similar to those that a slug might make. When you moved the leaves and the potato, did you see any of these holes?

What happened to the sow bugs and the pill bugs when you removed the black piece of paper and exposed them to the light? The animals may have run under the leaves or potato when you exposed them to the light. They prefer to live in dark places where predators like birds can’t see them.

When you moved the container and picked up the bugs, this is when the big differences between pill bugs and sow bugs started to show. When pill bugs are threatened, they roll up into a ball like an armadillo. This allows them to protect their heads by tucking it into the ball. Some species of sow bugs also roll a little, but they are more likely to play dead. If you pick up a sow bug, it may stay flipped on its back and slightly rolled up for a minute or more before it starts moving and turns over again.

Going Further

How could you design the ideal sow bug or pill bug habitat? What elements would you put in?

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