Should You Get Rid of Woodlice (Pill Bugs)?
Woodlice Visit Your Home in Autumn
You are most likely to notice woodlice in your home in the fall. They normally live out-of-doors amongst garden leaf litter or in dark, damp crevices or under stones. As the weather becomes cooler, they move indoors looking for a warmer place to help them survive through the winter months.
Some human homes are more attractive to them than others. They prefer places where they can live undisturbed in moist conditions and where they can have a reliable food source. If you have an infestation of roly-polies then you are have unwittingly provided these environmental conditions for your visitors. To prevent their stay becoming permanent you will need to eradicate this favorable habitat and proof your home against a further invasion.
Please Think Twice Before Getting Rid of Woodlice
Don’t be too hasty in getting rid of woodlice. To have them in your home may be one step too far, but in the garden they have a valuable role as part of a natural eco-cycle of decomposition and regrowth.
If you find them in the garden, please don't try to eradicate them; your garden benefits from their presence. Woodlice play a crucial role in soil ecosystems and they are harmless to humans.. The bodies of pill bugs provide a good source of calcium for animals higher up the food chain that eat them, for example some spiders, birds and frogs. They also have an essential role to play as decomposers in the Nitrogen cycle as shown in the diagram below.
Woodlice Look Like Tiny Armadillos
The scientific or Latin name for a woodlouse is Armadillidium vulgare. They may be small, but they have an important role to play in helping decompose the cellulose in wood and paper. They also help break down animal feces and turn it into useful manure. Their natural habitat is in leaf litter in woodland and shrub areas.
Some local names for woodlice are roly-polies and pill-bugs. These names relate to their ability to form little balls with their armor plating on the outside, protecting their soft innards. Their tough outer shell or exoskeleton has to be shed regularly to enable a woodlouse to grow and mature. The shedding is done in two stages. First it sloughs the rear half of its armor plating and then two or three days later it loses the front half of its exoskeleton. The shedding is done in stages in order to minimize the vulnerability of the creature during the short period it is without its armor.
Woodlouse in the Garden
Woodlice Provide Early Warning of Damp Problems
Although woodlice do not harm human beings themselves, a heavy infestation inside a building may result in damage to wood, paper and plaster. The picture below shows the kind of damage that can occur as a result of such an infestation.
Roly-polies can be helpful in that they alert you to the fact that there is a source of damp in your home. Woodlice need moisture to survive as they breathe through a kind of gills (like a fish) called a pseudo- trachea. Without any water source they would not have been able to successfully set up home in your building. It is essential to identify and remedy any source of dampness to successfully tackle a woodlice infestation. This should be done in tandem with other measures such as proofing your building to stop re-colonization by more roly-polies.
More Than 3,600 Species
There are more than 3,600 species of woodlice and they are found living all over the world.They are an ancient crustacean species that evolved from a water-based environment to being able to live on land. Different species have adapted to take advantage of a wide variety of habitats and this makes them difficult to eradicate. Their tough outer shell-like skin provides an effective barrier against most variations in temperature and humidity. However, the one thing they are unable to cope with is complete dryness.
The survival and reproduction of pill-bugs has been helped by their ability to eat a wide and varied diet. They are omnivores. Woodlice have a digestive system that allows them to eat things that would poison other species. They thrive on eating animal feces, molds, decomposing food scraps and cellulose.
Do you like woodlice?
Woodlice have the ability to increase in number quickly. In some species the female lays eggs three times a year with approximately fifty eggs laid each time. The common Garden Woodlouse species, found inside UK homes, lays one clutch of 150 eggs a year. The female woodlouse retains the eggs in a pouch on her body until they hatch. The hatchlings start life measuring approximately 2 millimeters.
The Choice Chamber Experiment
Various experiments have been carried out to determine the type of habitat most favored by woodlice. A simple experiment known as the “choice chamber” can be used to demonstrate the creature’s preferred environment. A container with either two or four compartments is used. Each one is differentiated so that the woodlice can make a choice between moist or dry, dark or light environments.
The video below of a choice chamber experiment demonstrates that woodlice prefer dark, damp conditions.
Woodlice Choice Chamber
Eradication and Proofing
Professional pest control operatives may use chemicals to poison and kill woodlice. However, without removing their habitat and food source, a new generation of woodlice will return to take over the newly vacant territory. In order to achieve permanent eradication it is necessary to maintain dry environmental conditions. In the short term this can be achieved through the use of salt barriers. A half inch border of salt poured across external doorways will cause them to dehydrate as they crawl across it.
In the longer term it is necessary to identify and replace areas of rotten timber. Cellulose in wood is one of their preferred food sources. You will need to fill any cracks or holes around windows and skirting boards with decorator’s caulk to prevent woodlice from finding new hiding places.
You may still want to control pill bugs. If so, try out the organic method shown in the video below. It uses cut halves of potatoes or melons to attract the woodlice. it is a non-toxic method of pest control and so is safe to use if you have pets or children.
Organic Pill Bug Control Using a Potato Trap
What Eats Woodlice?
There are many natural predators of woodlice. These include shrews, toads, centipedes, some spiders, ground beetles and parasitic flies. A healthy garden will have a balance of predators and prey, so there is no need to kill any woodlice outdoors yourself. Woodlice help to recycle dead plant and vegetable matter.
Woodlice occasionally come into houses from gardens, but they are unable to survive for long indoors unless they find a damp place to shelter. So remove any damp or rotting wood in your home and you are unlikely to find woodlice there. Those you do encounter can be retuned unharmed to their natural environment, your back-yard.
Would Salt Deter Slaters?
Slaters is another local name (Australian) for woodlice and pill-bugs. Using salt to deter roly-polys is an old folk remedy for infestations. The idea is that as woodlice crawl across a line of salt, their bodies become dehydrated and they die. I have tried this remedy, but not found it very effective. The advantage of salt is that it is a safer alternative to using poisonous chemicals if you have pets or children in your household.