Guest post blog by Sarah Gerhardt
When you turn over a stone or sift through your compost heap, you’ll often see tiny, often grey, armoured creatures scuttling away. They are woodlice and far from being garden pests. These hardworking recyclers help keep your garden healthy.
What Are Woodlice?
Despite looking like insects, woodlice are actually crustaceans, related to crabs and shrimps. Most crustaceans live in the water whereas the woodlouse developed to live on the land. This makes it quite unusual amongst its cousins. While they no longer live in the water, woodlice still require a lot of moisture as their bodies lose water rapidly. This is why they are usually found in dark, damp areas. Woodlice are ancient creatures, fossils show that they were already around 100 million years ago – an incredible testimony to their ability to adapt and evolve.
As is typical for crustaceans the outer skeleton of woodlice is shell-like, made up of segments, and is shed multiple times as the woodlouse grows. There are 30 species of woodlouse in the UK, some brown, some grey and some even pink in colour. Woodlice go by several different common names such as slater, sow bug, roly-poly or pill bug, the latter two alluding to the fact that some woodlice can roll into a sphere.
Common species in the UK include the rough woodlouse (Porcellio scaber), the shiny woodlouse (Oniscus asellus), the striped woodlouse (Philoscia muscorum), the pygmy woodlouse (Trichoniscus pusillus) and the pill woodlouse (Armadillidium vulgare), which can roll into a ball as a defense mechanism or to conserve moisture.
Nature’s Clean-Up Crew
Woodlice feed on decaying organic matter such as fallen leaves, rotting wood, decomposing vegetables and fruit, fungi and even occasionally dead animals in advanced stages of decomposition. In doing so they speed up decomposition by breaking down tough plant material into smaller particles.
In autumn they help process the huge amounts of leaf litter coming off trees. Woodlands would struggle to recycle their own waste if it was not for the help of woodlice. Nutrient cycling would slow and soil fertility would drop. Woodlice are extremely helpful in compost heaps where they process woody and dry materials that worms cannot manage and they help to create rich, crumbly compost. The tiny recyclers also enrich the soil as their droppings add nutrients and improve soil structure. They are a food source for birds, frogs, toads, beetles, and centipedes.
Some of the favourite foods of woodlice are fungi and moulds. By consuming mould-covered materials they help control fungal overgrowth and are sometimes introduced to closed systems such as terrariums and vivariums where mould can be a problem. The armoured bugs essentially act as cleaners in these systems. They recycle the waste and eat the moulds, keeping the ecosystem balanced and clean.
Will They Eat My Plants?
Gardeners who find woodlice in their flower pots and seed trays may worry that they are harmful to their plants. However, woodlice rarely damage living plants and only under certain conditions. They much prefer to feed on decaying matter and they are very unlikely to touch healthy, mature plants.
There is potential for them to cause damage if there is not enough rotting material available and live plants are in a very damp space. In these situations woodlice may nibble on tender seedlings, damaged roots or soft, decaying stems. This could happen in overwatered pots or poorly ventilated greenhouses, so essentially in environments where plants are already struggling. Soft fruit such as strawberries may get damaged by woodlice if they are resting on damp ground. The solution is not to kill the woodlice but to improve the growing environment: increase airflow, reduce moisture, lift fruit off the damp and improve the overall hygiene.
Why Do They Come Indoors?
Sometimes woodlice wander inside houses, especially during dry spells or when there is damp indoors. They are looking for moisture which their bodies need to survive. Don’t panic if you find woodlice in your kitchen. They don’t bite, sting, or spread disease. Usually, they won’t survive long indoors as it’s too dry and lacks their natural food.
Misconceptions around woodlice include that they eat wood furniture or beams. This is where woodlice get confused with woodworm, the larvae of a beetle that will damage furniture. Woodlice only eat decaying, moist wood. They will not damage the wooden structures in the house. It is also a myth that they invade panties or stored food cupboards. Woodlice are only interested in decomposing wet food, not in any dry storage foods.
Understanding this helps to prevent unnecessary pest control measures that do more harm than good. If woodlice have entered the house, remove them gently and release them outside. Reduce indoor damp and block small gaps around doors and skirting boards.
Encourage Woodlice in the Garden
Woodlice are an important part of garden biodiversity and play a vital role in nutrient cycling. To encourage them create damp, dark and sheltered spaces where they can thrive. This could be a compost heap or log pile. Avoid the overuse of pesticides.
Woodlice are often overlooked creatures whose quiet work promotes efficient composting, healthy soil and a balanced garden ecosystem. The next time you see one scurrying away, consider it a tiny ally doing its bit for your garden.
About the author: Sarah Gerhardt is a gardener, linguist and punk musician based in Edinburgh. She was head gardener at the Dean Gardens, Edinburgh for 9 years and runs her own gardening business Gerhardt’s Garden Service. Find out more via her Linktree: https://linktr.ee/gerhardtsgardenservice