Roly poly bugs are a common and curious sight in backyards and gardens around the world. These small, segmented creatures frequently spark intrigue, especially among children, as they tumble across damp soil or hide beneath garden debris. Their widespread presence makes them a familiar part of many outdoor environments. While they might seem like simple insects, there is much more to understand about what these interesting organisms are and the role they play in nature.
More Than Just a Bug
Roly poly bugs are not actually insects; they are terrestrial crustaceans. They belong to the order Isopoda, making them more closely related to shrimp, crabs, and lobsters than to typical garden insects like beetles or ants. These fascinating creatures are uniquely adapted to living entirely on land, unlike most of their aquatic relatives.
Roly polies are often recognized by several common names, including “pill bugs” or “woodlice,” with “sow bugs” being another related but distinct group. While pill bugs can roll into a tight ball, sow bugs generally cannot, due to slight differences in their body structure. Their physical appearance includes an oval, segmented body, typically gray to brownish in color, with seven pairs of legs and two pairs of antennae. They typically measure between 0.2 to 0.7 inches (0.5 to 1.8 cm) in length. Like their aquatic kin, they breathe through gill-like structures, which necessitates a moist environment for their survival.
Life in the Soil
Roly poly bugs primarily inhabit damp, dark environments, such as under rocks, logs, leaf litter, and other decaying organic matter. Their gills must remain damp to function properly. They are most active at night when humidity levels are higher, helping them to avoid desiccation.
These organisms play a significant role in their ecosystems as detritivores. They feed mainly on decaying plant material, fungi, and algae, acting as natural recyclers. By breaking down dead organic matter, roly polies contribute to the process of nutrient cycling, returning valuable nutrients to the soil for plants to utilize. Some species even consume their own feces, a behavior called coprophagy, which may help them retain essential minerals like copper. Their sensitivity to environmental shifts also makes them useful biological indicators for the health of the ecosystems they inhabit, and an interesting characteristic is their ability to absorb and crystallize heavy metals like copper, zinc, lead, and arsenic within their bodies, which can help in cleaning up contaminated soil.
Unique Behaviors and Misconceptions
One of the most recognized behaviors of roly poly bugs is their ability to roll into a tight, protective ball, a defense mechanism known as conglobation. This action shields their softer undersides from potential predators and helps them conserve moisture, preventing them from drying out. This unique ability is the origin of their common “roly poly” nickname.
There are several common misunderstandings about roly poly bugs. They are generally harmless to living plants and are not considered pests. In fact, their decomposition activities are beneficial for gardens, enhancing soil quality and promoting a healthy environment for plant growth. They do not bite or sting, posing no threat to humans or pets. While they occasionally feed on tender plant seedlings if other decaying matter is scarce, this is not their primary diet. If roly polies venture indoors, they typically do not survive for long due to the lack of sufficient moisture required for their survival.