Armadillidium vulgare
Encyclopedia
Armadillidium vulgare, the (common) pill-bug or (common) pill woodlouse, is a widespread Europe
an species
of woodlouse
. It is the most extensively investigated terrestrial isopod species.
s such as Glomeris marginata
. It can be distinguished from Armadillidium nasatum and Armadillidium depressum, the only other British species in the genus, by the gap that A. nasatum and A. depressum leave when rolling into a ball; A. vulgare does not leave such a gap.
s and algae from tree bark and walls.
It is able to regulate its temperature
through its behaviour, preferring bright sunshine when temperatures are low, but remaining in shadow when temperatures are high; temperatures below -2 C or above 36 °C (96.8 °F) are lethal to it. A. vulgare is less susceptible to cold during the night, and may enter a state of dormancy
during the winter in order to survive temperatures which would otherwise be lethal.
, A. vulgare is very common in southern
and eastern England
, but is more confined to coastal areas in the north. Similarly, in Ireland
, A. vulgare is common in the south and east, but rarer in the north and west.
A. vulgare has been introduced to many locations in North America
, where it may reach population densities
of up to 10,000 individuals per square metre. It is now one of the most abundant invertebrate species in California
coastal grassland
habitats. It has also been introduced, to a lesser extent, to sites across the world.
in areas throughout the U.S., typically among children. Among adults, they are often seen as unwanted (but essentially harmless) home pests. Keeping a pet pill bug requires a very moist habitat with limited light and lots of decaying plant matter. They can often live up to three years.
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of woodlouse
Woodlouse
A woodlouse is a crustacean with a rigid, segmented, long exoskeleton and fourteen jointed limbs...
. It is the most extensively investigated terrestrial isopod species.
Description
Armadillidium vulgare may reach a length of 18 millimetre (0.708661417322835 in), and is capable of rolling into a ball when disturbed; this ability, along with its general appearance, gives it the name pill-bug and also creates the potential for confusion with pill millipedePill millipede
Pill millipedes make up two orders of millipedes, often grouped together into a single superorder, Oniscomorpha. The name Oniscomorpha refers to the resemblance of pill millipedes to certain woodlice, namely the pillbugs of the family Armadillidiidae, also called "potato bugs", "doodlebugs", or...
s such as Glomeris marginata
Glomeris marginata
Glomeris marginata is a common European species of pill millipede. It is a short millipede, rounded in cross-section, which is capable of rolling itself up into a ball when disturbed. This behaviour is also found in the pill woodlouse Armadillidium, with which G...
. It can be distinguished from Armadillidium nasatum and Armadillidium depressum, the only other British species in the genus, by the gap that A. nasatum and A. depressum leave when rolling into a ball; A. vulgare does not leave such a gap.
Ecology
A. vulgare is able to withstand drier conditions than many other woodlouse species, and is restricted to calcareous soils or coastal areas. It feeds chiefly on decaying plant matter, but also grazes lichenLichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
s and algae from tree bark and walls.
It is able to regulate its temperature
Thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different...
through its behaviour, preferring bright sunshine when temperatures are low, but remaining in shadow when temperatures are high; temperatures below -2 C or above 36 °C (96.8 °F) are lethal to it. A. vulgare is less susceptible to cold during the night, and may enter a state of dormancy
Dormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
during the winter in order to survive temperatures which would otherwise be lethal.
Distribution
The native distribution of A. vulgare ranges across Europe, especially in the Mediterranean region . In the United KingdomUnited Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, A. vulgare is very common in southern
Southern England
Southern England, the South and the South of England are imprecise terms used to refer to the southern counties of England bordering the English Midlands. It has a number of different interpretations of its geographic extents. The South is considered by many to be a cultural region with a distinct...
and eastern England
East of England
The East of England is one of the nine official regions of England. It was created in 1994 and was adopted for statistics from 1999. It includes the ceremonial counties of Essex, Hertfordshire, Bedfordshire, Cambridgeshire, Norfolk and Suffolk. Essex has the highest population in the region.Its...
, but is more confined to coastal areas in the north. Similarly, in Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, A. vulgare is common in the south and east, but rarer in the north and west.
A. vulgare has been introduced to many locations in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, where it may reach population densities
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...
of up to 10,000 individuals per square metre. It is now one of the most abundant invertebrate species in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
coastal grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
habitats. It has also been introduced, to a lesser extent, to sites across the world.
Relationships with people
Because of their unusual yet non-threatening appearance, some Armadillidium vulgare are kept as petsPETS
PETS may be an acronym for:* Pet Travel Scheme, which allows animals to travel internationally without quarantine* Pets Evacuation and Transportation Standards Act...
in areas throughout the U.S., typically among children. Among adults, they are often seen as unwanted (but essentially harmless) home pests. Keeping a pet pill bug requires a very moist habitat with limited light and lots of decaying plant matter. They can often live up to three years.