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Why You Shouldn't Kill Woodlice (AKA Pill Bugs, Roly-Polies)

I have "green-fingers," and love my garden. I enjoy watching wildlife and being outdoors.

Trying to Get Rid of Woodlice?

Woodlice are autumn visitors to your home. Please don't be too quick to try to kill them. You may not want pill bugs in your house, but they are very helpful in your garden. Woodlice are harmless to humans and they're an important part of nature's cycle of decomposition and regrowth. The bodies of roly-polies also provide a good source of calcium for spiders, birds and frogs.

Their normal home is outdoors amongst garden leaf litter, in dark, damp crevices, or under stones. As the weather gets cooler, they move into your house looking for somewhere warm to help them survive the winter months.

Woodlouse (roly-poly or pill bug) are great for your garden and act as nature's recyclers.

Woodlouse (roly-poly or pill bug) are great for your garden and act as nature's recyclers.

Where Do Woodlice Live? What Do They Eat?

Woodlice (Armadillidium vulgare) may be small, but they have a key role in helping the decomposition of 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. There are more than 3,600 species of woodlice, and they can be found all over the world. The book Woodlice gives fascinating detail about their life and habits. They are an ancient crustacean species that have adapted to take advantage of a wide variety of living conditions. This makes them difficult to eradicate.

Their tough outer shell-like skin provides an effective barrier against most levels of temperature and humidity. The one chink in their armour is when they encounter completely dry conditions. They are unable to survive in bone-dry dessert-like environments. Woodlice are omnivores, and have a wide and varied diet. Their specialized digestive system enables them to eat things that would poison other species. They thrive on eating animal feces, molds, decomposing food scraps and cellulose.

Woodlice eat damp, soft, rotten wood. They are nature's composters.

Woodlice eat damp, soft, rotten wood. They are nature's composters.

Why a Woodlice Infestation May Be a Sign of Dampness Problems

Roly-polies alert you to the fact that there is a source of dampness in your home. They need moisture to survive, as they breathe through a structure similar to a fish's gill called a pseudo-trachea. Without any water source, they would not have been able to successfully set up a home in your building.

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. Although woodlice do not harm human beings themselves, a heavy infestation inside a building may result in damage to already-decaying wood, paper and plaster. The picture above shows the kind of damage that can result.

Female woodlice carry their offspring in their marsupia.

Female woodlice carry their offspring in their marsupia.

How Long Do Woodlice Live For? How Quickly Do They Reproduce?

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 often 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 two millimeters.

Woodlice live for about two years, although some species can live for up to four. Their lives may be cut short if they are naturally predated or deliberately poisoned by human pest controllers.

Don't Kill Roly Poly Pill Bugs You Need Them In Your Garden

How to Eradicate Woodlice From Your Home (And Prevent Them From Returning)

Professional pest control technicians are costly and may use harmful chemicals to poison and kill woodlice. While this may be effective in the short term, a new generation of woodlice will likely return to take over the newly vacant territory if you don't remove their indoor habitat and food source.

Pill bugs prefer places where they can live undisturbed in moist conditions, so to prevent their stay becoming permanent, you need to change these conditions and proof your home against future roly-poly visits.

  • Identify and remedy any source of dampness.
  • Proof the building to prevent re-colonization by more roly-polies.
  • To achieve permanent eradication, maintain dry environmental conditions.

If you still want to control pill bugs, try 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? Do They Have Predators?

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. They prefer places where they can live undisturbed in moist conditions. To prevent their stay becoming permanent you will need to change these favorable conditions and proof your home against a future roly-poly visit.

Does 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.

Can Vinegar Kill Woodlice?

Household vinegar is a weak acid. It can be used as a cleaning agent at home as it removes grease. For example, some people use it to clean dirty windows. However, it cannot be used to kill roly-polys. Woodlice are unaffected by vinegar as they simply roll up into a protective ball and the liquid is unable to get through their hard outer shell.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.