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| Pill Bug (Armadillidium vulgare). Rowan County, North Carolina. |
Pill Bugs are not really bugs; they are not even insects. They are actually terrestrial Crustaceans and like their better-known relatives, lobsters and crabs, they have gills. Pill Bugs must keep their gills moist to exchange oxygen and carbon dioxide. Because of this requirement these interesting little animals are restricted to humid environments. Gills tell a story about the evolutionary history of Pill Bugs. Their ancestors lived in ancient oceans before the time of the dinosaurs and crawled onto land 300 million years ago to eventually become our present-day Pill Bugs. Pill Bugs are detritivores, and live in the upper layers of the soil. They consume dead plant material and the microscopic decomposers found on the rotting vegetation.
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| Pill Bug rolled up in protective posture. Rowan County, North Carolina. |
Pill Bugs are known by a number of common names including
Roly-polys, Armadillo Bugs and Woodlice. The name woodlouse comes because they are often found under rotting logs. The
names Armadillo Bug and Roly-poly refer to the Pill Bug habit of rolling into a
ball as a protective behavior. When they are rolled up, Pill Bugs resemble pills giving rise to that common name.
Whether they are called Woodlice, Armadillo Bugs, Roly-polys or Pill Bugs these creatures are classified in the Order Isopoda. The name Isopoda comes from the Greek meaning “same feet” because each of their seven sets of legs are the same size. Contrast this with crabs (Order Decapoda) that have legs of vastly different sizes, some specialized for feeding (claws), some for walking and some for swimming (swimmerets). The most common Pill Bug in our area is Armadillidium vulgare. This native of Europe has spread around the world with humans and is found in temperate regions of six continents.
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| A group of Pill Bugs in soil. Many different sizes and colors are present. Rowan County, North Carolina. |
Adult Pill Bugs are about ¾ inch long and dark brown or gray in color with a segmented exoskeleton that covers their upper surface. They have a two compound eyes and a pair of antennae on the head. Each of the seven main body segments has two legs. Pill Bugs take about a year to mature and must molt their exoskeleton to grow to a larger size. After molting Pill Bugs are lighter in color but darken up quickly. It is common to find a wide range of Pill Bug sizes because they are always growing through their different stages.
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| Pill Bug on a leaf. Rowan County, North Carolina. |
Pill Bugs do not bite or sting nor do they transmit human diseases. Because of their benign nature and their
downright cuteness, Pill Bugs are kept as pets by people around the world. If you want to see some pill bugs, look under
logs or rocks. All the Pill Bugs photographed
for this blog were sleeping under a flowerpot on our porch. Take a look, and you will find these
fascinating creatures quietly living their lives.
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