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By Courtney Jane Brown
Geographic Range
You have probably seen them in your basement or garden, for they live under stones and bark in damp places. While they exist in large numbers here in North America, they also reside in the wettest areas of Germany.
Biogeographic Regions:
nearctic 
(native ); palearctic (native ).
Habitat
Pill bugs hide in damp places during the day and are active at night. Under moist areas such as bark and stones, they make their burrow (living quarters.) One of the pill bugs' most surprising characteristics is that they have such a wide distribution pattern. "Home" can be a forest, garden, or basement.
Terrestrial Biomes:
savanna or grassland ; forest .
Physical Description
Their light shell-like crustaceous exterior is usually a drab earthy color. Pill bugs found in North America range from gray to brown. However, those with habitats in Europe have large red dots, which give them protection by conferring a resemblance to black widow spiders. Pill bugs have five abdominal segments which are distinct dorsally. Their first antennae are vestigial.
Reproduction
A. vulgare reproduce on land as opposed to in water. Eggs develop in a brood pouch filled with fluid, from which fully developed young are released. They produce between one and two broods. The number produced depends on the size and condition of the female, who may cease to grow under stress due to excessive hydration, which reduces the chance of a second reproduction. Ironically, when the food supply is short, the offspring grow larger.
Behavior
Pill bugs live in an arrangement where the father reigns supreme. He guards the burrow in which the family lives. The monogamous pair (the mother and father) gather food for the entire family. Then, the entire family cleans the burrow of faecal pellets. Faecal pellets are carried outside the burrow around the entrance. In February the family disbands and the young set out to make new families of their own. However, the juveniles will always stay within 10 to 100m of the family's main burrow.
Food Habits
A. vulgare, like most isopods, are omnivorous. They feed on fungi, live or dead plants and animals. Special treats for pill bugs are monocotyledonous leaves. All isopods increase decomposition by processing leaves through their alimentary canal. It is not uncommon for pill bugs to shift from one type of food to another, for during a drought they turn from being vegetarians into scavengers.
Predation
- centipedes
- spiders
- ants
- birds
- amphibians
- anything that eats invertebrates
They are famous for curling up into a tight ball for a defense mechanism. Some may secrete a substance which discourages spiders. The most common defense among all of them is to remain inconspicuous.
Ecosystem Roles
These animals are part of the community of species that break down dead plants and animals.
Key ways these animals impact their ecosystem:
biodegradation .
- Pillbugs and sowbugs have microbes in their guts that allow the crustacean to digest plant material.
Economic Importance for Humans: Negative
Pillbugs may occasionally eat small plants as they germinate, causing some trouble in gardens.
Economic Importance for Humans: Positive
Pill bugs living in gardens help circulate soil, although they may also eat small plants.
Conservation Status
IUCN Red List: [link]:
Not Evaluated.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
State of Michigan List: [link]:
No special status.
Pill bugs are quite common and have no special conservation status.
Other Comments
They are famous for curling up into a tight ball for a defense mechanism. Some may secrete a substance which discourages spiders. The most common defense among all of them is to remain inconspicuous. They have a life span of up to five years!
Contributors
Courtney Jane Brown (author), University of Michigan.
