The small, grey, shelled creatures often encountered in gardens are terrestrial crustaceans, known as isopods. They are more closely related to crabs and shrimp than to true insects. The two most frequent types found are the Pill Bug (Armadillidium vulgare) and the Sow Bug (Porcellio scaber). They thrive in moist, dark environments and are a natural component of the garden ecosystem.
Identification of Common Grey Garden Creatures
The easiest way to distinguish between the two is by observing their behavior when disturbed. The Pill Bug, often called a “roly-poly,” can curl its body into a tight, defensive sphere (conglobation) to protect its softer underside. Pill Bugs also have a smooth, rounded rear end that lacks prominent projections.
In contrast, the Sow Bug cannot roll into a ball and will scurry away when disturbed. Sow Bugs are typically flatter and more oval-shaped. A distinct feature is the presence of two prominent, tail-like appendages, called uropods, protruding from the rear. Both species are dark to slate grey, measure about one-third to three-quarters of an inch, and possess seven pairs of legs.
Decomposer or Pest Understanding Their Role
These isopods serve a beneficial function as primary decomposers. Their main diet consists of decaying organic matter, such as dead leaves, rotting wood, and plant debris. By consuming this material, they help break it down into rich soil components, aiding in the recycling of nutrients back into the earth.
However, they become pests when population density is high or food sources are scarce, often linked to excessive moisture. They begin to feed on tender, living plant tissue, typically targeting vulnerable seedlings, fine roots, or the surface of fruits and vegetables resting on damp soil, such as strawberries. Damage usually appears as ragged holes or superficial scarring on plant parts in contact with the ground. Because they are nocturnal, observing the damage often requires checking the garden with a flashlight after dusk.
Non-Chemical Methods for Population Management
Managing problematic populations focuses on altering the environmental conditions they require to thrive. Since isopods rely on high moisture levels to breathe and survive, reducing excess water is the most effective first step. This can be achieved by improving soil drainage, watering early in the day so the surface dries before nightfall, and switching from overhead sprinklers to drip irrigation.
Removing potential hiding and breeding sites near vulnerable plants is another effective cultural control measure. This includes clearing away piles of leaf litter, grass clippings, and old boards or stones where they shelter. If mulch is used, apply a thinner layer or pull it back several inches from the base of seedlings and plant stems.
Physical Barriers
Physical barriers can also be employed to protect individual plants.
- Applying a thin, dry line of food-grade diatomaceous earth around the perimeter of a bed can desiccate the isopods as they cross it.
- Copper tape can be placed around raised beds, as the metal creates a mild electrical charge that deters the creatures.