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.
Known Predators:
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.
Other Physical Features: ectothermic ; bilateral symmetry
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
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 )
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.
Primary Diet: carnivore (Scavenger ); herbivore (Folivore , Frugivore ); mycophage ; detritivore
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!
Pill bugs are quite common and have no special conservation status.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Pillbugs may occasionally eat small plants as they germinate, causing some trouble in gardens.
Pill bugs living in gardens help circulate soil, although they may also eat small plants.
These animals are part of the community of species that break down dead plants and animals.
Ecosystem Impact: biodegradation
Mutualist Species:
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.
Armadillidium vulgare, known as pill beetles or roly polies, are part of the Armidillididae family (Hopkins, 1991). Although A. vulgare is widespread across most terrestrial landmasses, the species actually originates from the Mediterranean area and has adapted to survive in temperate environments where moisture saturates both the soil and atmosphere (Smigel, 2008). Physical characteristics of A. vulgare include a tough outer cuticle made of chitin that protects its soft ventral side, flattened/round segmented back, sharply angled antennae, 7 segments on its pereon (thorax), and 6 segments on its pleon (abdomen) (Hopkins, 1991). On its abdomen, there are a pair of limbs on the first two segments of the pleon (called pleopods) and are responsible for excretion, reproduction, and respiration (Hopkins, 1991). The last segment on the pleon consist of limbs called the uropod that serves a sensory/defensive function (Hopkins, 1991). A. vulgares is oval in its body shape and varies in length at different stages in its life, however, male and female species weigh the same (Harding, 1985). Juveniles are between 5 mm to 7 mm in length while young adults are about 10 mm in length and 5 mm in width (Harding, 1985). Large female individuals of A. vulgare at ages 2-3 years old, usually produce 2 broods per season, while smaller females of the same species produce 1 brood per season (Lawlor, 1976). When impregnated, females develops a ventral pouch to store her eggs and after a few day the juveniles hatch inside the pouch (Lawlor, 1976). Once hatched the juveniles absorb the fluid in the pouch and emerge. In the first molting of the juvenile, the 7th pair of its legs are developed and the species will continue to molt its cuticle in order to continue growing in size (Lawlor, 1976). Once born, A. vulgare has a life expectancy of a few years (Le Clec’h, 2013) with some individuals of A. vulgare living up to 2 years in captivity (Chevalier, 2011).
Armadillidium vulgare are detritivores, meaning that they consume dead organic matter (Le Clec’h, 2013). A. vulgare consumes decaying leaf litter, but under stressed condition where no better option is available they may become graniverous and even cannibalistic (Le Clec’h, 2013). In one experiment A. vulgare individuals were starved for 3 months and were then left with another individual; the experiment resulted in one individual becoming cannibalistic and eating the other. (Le Clec’h, 2011).
Many of the patterns in A. vulgare’s behavior are dictated by the species’ struggle to maintain its body moisture and avoid desiccation (drying out) (Moriyama, 2004). This species usually lives beneath dead leaf litter or stones and even conglobate (roll up into ball) to prevent any unnecessary desiccation (Smigel, 2008). When A. vulgare experiences a strong vibration or pressure, it conglobates, covering its soft ventral side by rolling into a ball and exposing only a tough outer cuticle for protection against predators (Smigel, 2008). Interestingly, when in dry soils or in in temperatures above 40˚C, A. vulgare has been found to conglobate, however, when found in moist soil A. vulgare was found to be unconglobated, meaning that conglobation may not only be for defensive purposes, but also for water retention (Smigel, 2008).
When moisture levels are above 10% and leaf litter (dead organic material) present, A. vulgare populations can be expected (Smigel, 2008). A. vulgare individuals contain a pheromone that may give notice to surrounding congeners (like-species) and have them aggregate; often times, this aggregation can exceed 70+ individuals in a span of 10 minutes (Broly, 2012). This massive aggregation is a water retention mechanism that prevents water loss by covering individuals with their bodies (Broly, 2012).
When considering A. vulgares’ ecological importance, its role as a detritivore and ability to remediate make it a valuable species of animal to protect (Paoletti, 1999). As a detritivore, A. vulgare drives nutrient cycling by breaking down organic debris to nutrients that can be readily absorbed by plants (Paoletti, 1999). A. vulgare also has the ability to partially remediate heavy metal contamination by taking in heavy metals and storing deposits on their mid-gut, which helps in the recovery of areas contaminated with toxic heavy metals, making it a great bio-indicator for the health of an ecosystem (Paoletti, 1999).
Armadillidium vulgare, the common pill-bug, potato bug, common pill woodlouse, roly-poly, slater, doodle bug, or carpenter, is a widespread European species of woodlouse. It is the most extensively investigated terrestrial isopod species.[2]
Armadillidium vulgare may reach a length of 18 millimetres (11⁄16 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 millipedes such as Glomeris marginata.[3] It can be distinguished from Armadillidium nasatum and Armadillidium depressum by the gap that A. nasatum and A. depressum leave when rolling into a ball; A. vulgare does not leave such a gap.[4]
Armadillidium vulgare is able to withstand drier conditions than many other woodlouse species, and is restricted to calcareous soils or coastal areas.[3] It feeds chiefly on decaying plant matter, but also grazes lichens and algae from tree bark and walls.[5]
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 (28 °F) or above 36 °C (97 °F) are lethal to it.[6] 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 that would otherwise be lethal.[6]
The native distribution of A. vulgare ranges across Europe, especially in the Mediterranean Basin.[2] In the United Kingdom, A. vulgare is very common in southern and eastern England, but is more confined to coastal areas in the north.[7] Similarly, in Ireland, A. vulgare is common in the south and east, but rarer in the north and west.[7]
A. vulgare has also been introduced to many locations in North America, where it may reach population densities of up to 10,000 individuals per square metre (900 individuals per square foot).[8] It is now one of the most abundant invertebrate species in California coastal grassland habitats.[9] It has also been introduced, to a lesser extent, to sites across the world.[2]
Because of their unusual yet non-threatening appearance, some Armadillidium vulgare are kept as pets in areas throughout the world. Different lineages are bred, usually in regards to color, in order to provide stock to hobbyists. One supposed variation, "Punta Cana," is often referred to as Armadillidium sordidum, while others insist it is a variety of A. vulgare.[10] Keeping a pet pill bug requires a very moist habitat with limited light and abundant decaying botanical matter.[11] They can often live up to three years.[12] Among non-hobbyist adults, they are often seen as unwanted (but essentially harmless) home pests.[12]
Most metazoans have circular mitochondrial genomes, but A.vulgare has an unusual combination of both circular and linear mitochondrial DNA.[13]
Armadillidium vulgare beginning to unroll from its defensive posture
A related isopod (sowbug) with its clutch on its belly
Solid grey A. vulgare as adults
Armadillidium vulgare, the common pill-bug, potato bug, common pill woodlouse, roly-poly, slater, doodle bug, or carpenter, is a widespread European species of woodlouse. It is the most extensively investigated terrestrial isopod species.
