Roly polys, commonly known as pill bugs or woodlice, are familiar inhabitants of gardens and damp environments. Despite their common names, these creatures are not insects; they are terrestrial isopods, a type of crustacean more closely related to lobsters and crabs. The most widespread species is Armadillidium vulgare. They are recognized by their segmented, oval bodies and their distinctive ability to curl into a tight ball when disturbed, a defense mechanism called conglobation.
Average Lifespan of Roly Polys
Roly polys generally live for two to five years. While some sources indicate an average wild lifespan of around 1.5 to 2 years, longer lifespans of up to three years are frequently observed in natural settings. In controlled environments, such as those maintained by hobbyists, roly polys can survive for up to three years, sometimes even longer, due to consistent access to resources and protection from external threats.
Factors Influencing Roly Poly Lifespan
The longevity of a roly poly is significantly shaped by its surrounding environment, particularly the availability of moisture and shelter. As terrestrial crustaceans, they possess gill-like structures for breathing, which necessitate a consistently humid environment to function. They thrive in dark, damp locations such as under rocks, logs, leaf litter, and in compost piles, which help them avoid desiccation. Exposure to dry conditions or direct sunlight quickly dehydrates them, proving fatal as they cannot regulate their body temperature.
Food availability also directly impacts their survival. Roly polys are detritivores, primarily consuming decaying organic matter like dead plants, wood, and fungi.
Predation poses a constant threat, reducing roly poly populations. Common predators include birds, spiders, centipedes, frogs, toads, and small mammals like shrews. However, they become particularly vulnerable during the molting process when their exoskeleton is soft and they cannot fully conglobate. Additionally, like all living organisms, roly polys are susceptible to diseases, including viral infections such as iridoviruses, which can lead to mortality.
The Roly Poly Life Cycle
Roly polys undergo a distinct life cycle that begins with eggs. Female roly polys possess a specialized brood pouch, called a marsupium, located on their underside, where they carry their eggs. A female can lay anywhere from a few dozen to up to 200 eggs, which develop within this moist, protected environment for several weeks to a few months.
After hatching, the young roly polys, known as mancae, are miniature versions of the adults, though often paler and with fewer legs initially. They may remain in the mother’s pouch for a short period after hatching, continuing to develop before venturing out independently.
As they grow, roly polys must shed their rigid outer shell, or exoskeleton, through a process called molting. Unlike many other arthropods, they molt in two stages, first shedding the back half of their exoskeleton and then the front half a few days later, which helps minimize their vulnerability. This molting occurs multiple times, typically five to twelve times, before they reach adulthood, a stage usually attained after about one year.