Pill bugs, also known as roly-polies or woodlice, are common backyard inhabitants found beneath rocks and decaying logs. These small crustaceans are primarily beneficial organisms that play a significant role in maintaining soil health. While their diet consists mostly of dead organic material, they can occasionally shift their feeding habits to include living plants. Understanding this dual nature helps gardeners implement simple, preventative measures to protect vulnerable plants while appreciating their positive environmental contribution.
Pill Bugs as Decomposers
Pill bugs are classified as detritivores, meaning their function is to consume dead and decaying matter, or detritus. Their typical diet includes leaf litter, rotting wood, fungi, and other decomposing vegetation found on the soil surface. This feeding behavior is an important ecological process, breaking down organic material into smaller particles.
As they digest detritus, pill bugs help cycle nutrients back into the soil, enriching it for new plant growth. They contribute to healthy soil structure and composition. Their presence often indicates a large supply of organic matter, such as heavy mulch or compost, which is their preferred food source.
Conditions That Lead to Plant Damage
Pill bugs generally only feed on living plants when environmental conditions or population pressures force the change. As gill-breathing crustaceans, they require a moist environment to survive. When conditions become too dry, they seek internal moisture within tender plant tissues as a survival mechanism.
Damage typically occurs in two scenarios: high population density or a lack of preferred dead food. When numbers are high, decaying material becomes exhausted, leading them to search for alternative food sources. This risk is heightened during spring and summer when the natural leaf litter layer may be less abundant.
They target soft, succulent plant parts close to or touching the ground. Vulnerable items include tender seedlings, soft fruits like strawberries, and the lower leaves or stems of mature plants. Damage often appears as chewed holes or scraped areas on young plants, frequently occurring at night when pill bugs are most active.
Practical Steps for Population Management
Managing pill bug populations focuses on modifying the environment to make it less hospitable. Since they require constant moisture, reducing excessive dampness is an effective strategy. Watering plants early allows the soil surface to dry out by evening, discouraging nighttime activity.
Removing excess debris near garden beds limits their hiding spots and food supply. This involves clearing away thick layers of leaf litter, old boards, or excessive mulch from around vulnerable plants. Creating a buffer zone of dry soil or fine gravel around plant bases helps physically deter them.
For protecting newly planted seedlings, gardeners can use physical barriers. Sprinkling diatomaceous earth, which dehydrates the pill bugs upon contact, around the base of plants creates a lethal barrier. Alternatively, placing collars made of paper or plastic tubing around the stems of young plants prevents the pill bugs from climbing up to feed.