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Roly Polies (Armadillidiidae)

Roly Polies, also known as Pill Bugs, are small terrestrial crustaceans that are well known in most parts of the Americas. They are a Family of woodlice that has 15 recognized genera and over 260 different species. Due to their behavior and abundance, they are fascinating to study and learn more about. What can we find out about these multi-legged insects?

Physical Description and Behavior

Pillbugs are tiny bugs that have a segmented outer shell, two antennae, and are generally some shade of gray. While it is possible for them to be seen in other colors, it is usually a sign of a virus or stage of development. For instance, the colors white or blue can be seen due to the presence of a certain virus such as Iridovirus. When they molt, they can be a lighter gray or even a transparent white.

Fun fact: Pillbugs are able to roll themselves into balls similar to how armadillos do. This act is known as conglobation. Pill millipedes and cuckoo wasps do this as well, which seem to be a form of protection against predators. Vibrations and/or pressure may be the reason they do this, which can either make them hard to eat or else make them appear like surrounding rocks.

Pillbugs are often confused with their cousins, the sowbug (below). However, sowbugs are flatter and cannot roll into a ball.

Sowbug - Image Credit: Alex Bowen
Sowbug - Image Credit: Alex Bowen

Pillbugs are decomposers, consuming rotted wood, leaves, and occasionally other parts of plants. While doing this, they can temporarily remove toxic metals, such as Zinc, Lead, and Cadmium, from the soil. However, these metals are returned when the roly-poly dies. While they make good sources of food for local birds and other animals, due to them being nocturnal, they can be hard to find.

Habitat and Location

Pillbugs can be found all over the world, but are forced to be in locations close to water. They need moisture to be able to properly breathe through their gills, so it is not shocking to see that they don't really exist in more desert environments such as much of Africa. They are also generally not found in colder climates, such as Russia and Alaska.

To learn more about these abundant critters, check out the video below!

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