Roly poly bugs, also known as pill bugs or sow bugs, are terrestrial crustaceans, related more closely to shrimp than to insects. These small, armored creatures are decomposers, consuming dead organic matter like fallen leaves and plant debris. This speeds up decomposition and returns nutrients to the soil, contributing significantly to soil health.
Problems arise when populations become excessive, usually driven by persistently moist environments and abundant shelter. When decaying matter becomes scarce, or when populations are very high, they shift their diet to live plant tissue. This leads to damage, particularly on tender, newly sprouted seedlings, which they can consume overnight.
Roly poly bugs also target soft fruits and vegetables resting directly on the soil surface, such as strawberries, melons, and radishes. The damage appears as ragged holes or chew marks concentrated at the soil level, where they are most active during nocturnal foraging. Once this destructive behavior starts, intervention is necessary to protect vulnerable plants.
Long-Term Prevention Through Habitat Management
The most effective long-term strategy involves changing the environmental conditions that allow roly poly populations to thrive. These crustaceans require consistently damp, dark conditions to survive because they breathe through gills and quickly dehydrate without moisture. Reducing overall moisture and humidity in the garden is the foundational step in prevention.
Adjusting watering practices significantly alters the habitat’s suitability. Switching from evening watering to morning irrigation allows the soil surface to dry out before the bugs become active at night. Improving drainage in garden beds eliminates the damp pockets where they congregate and reproduce.
Removing excess organic debris eliminates both their food source and primary daytime hiding spots. While mulch is beneficial for soil health, use it sparingly and keep a clear buffer zone around vulnerable plants. Regularly cleaning up fallen leaves, grass clippings, and old plant residue forces the bugs into less protected areas, where they are more susceptible to desiccation and predators.
Ensuring good air circulation near the soil surface also contributes to a drier environment. Elevating items that sit directly on the ground, such as stepping stones, potted plants, and firewood, removes the cool, moist shelter areas underneath them. A well-managed garden with less surface moisture and fewer large debris piles will naturally support a smaller population.
Immediate and Targeted Removal Techniques
When high populations are actively damaging plants, immediate, targeted removal methods quickly reduce their numbers.
Physical Trapping and Removal
A simple, non-chemical approach uses physical traps that exploit their need for dark, moist shelter. Traps can be made by placing hollowed-out halves of potatoes, cantaloupe rinds, or damp rolls of newspaper cut-side-down in the affected area. The bugs seek refuge and food inside the traps overnight, allowing for easy collection and relocation the following morning. For immediate disposal, a shallow container sunk into the soil with beer or a cornmeal mixture attracts the bugs, causing them to drown. Hand removal is also viable for small gardens, especially when scouting at night.
Barrier Methods
Physical barriers prevent the bugs from reaching susceptible plants. A perimeter of food-grade diatomaceous earth (DE) sprinkled around seedlings creates a lethal barrier; the sharp particles scratch the exoskeleton, leading to fatal dehydration. DE must be reapplied after watering or rain, as moisture renders it ineffective. Copper tape is another deterrent, as the metal reacts with the bugs’ bodies, delivering a small shock they avoid.
Organic Baits
If the infestation is severe, an organic, targeted bait is an option. Baits containing iron phosphate are effective against roly poly bugs, slugs, and snails. The bugs ingest the pellets, which disrupts their digestive system, causing them to stop feeding and eventually die within a few days. This bait is considered safer for pets and wildlife than chemical alternatives, as iron phosphate naturally breaks down into a soil nutrient.