UNWELCOME GUESTS

There are billions of creatures in our home compost bins but you can’t see most of them turning our garden and raw kitchen waste into wonderful compost. We are glad to see lots of worms, but occasionally we see less welcome visitors to our compost bins.
Don’t worry. There are simple ways of getting rid of these unexpected visitors and preventing their return.

The most common are:

Ants: they like a warm, dry sheltered place to make their nests. They help break down the material in your compost bin but are a nuisance when you want to use the finished compost. The easiest way to get rid of them is to empty your compost bin and pull apart all the material. (See Empty your Bin for the best way to do this). Use a long handled rake (some people are allergic to ant bites) to spread the contents of your bin out on the ground; try to pull fresh compostables to one side and finished compost to another. The ants will rush around trying to save their larvae and eggs. You can pour a kettle of boiling water over them.
Soak the ground underneath your compost bin so that it is really soggy, put back the bin and fork in all the fresh compostables and stuff that hasn’t turned into compost yet. Pour in a bucket of cold water.
If the ants are still milling around in the finished compost, spread it out thinly and leave it overnight. By morning they will all have gone and you can use the compost in the normal way.
To stop the ants returning to your bin, keep it wetter than normal: add lots of sappy green material, like grass mowings and vegetable trimmings; pour in a bucket of water every few days if the weather if hot and dry.
Ants will not be a problem in the winter.

Flies: sometimes when you lift the lid of a compost bin a swarm of little flies rises up. These will probably be fruit flies and they are annoying but harmless. They are attracted to the smell of rotting fruit and vegetable waste so the best way to get rid of them, and to stop them returning, is to cover the surface of the compostables with a spadeful of garden soil. Then they can’t smell the rotting material underneath. Don’t use commercial compost or mulch material as these are sterile and all the “good” creatures will not be able to live in that layer.
If you are putting in a lot of fruit waste, like spoilt windfall apples, try to cover it over with dry woody material such as shredded prunings or paper.

Fungi: occasionally unexpected fungi appear round the edges of a compost bin. This usually happens in a New Zealand box where the composting material is left for a long time. In a plastic bin, where it takes a year to make compos , there is not time for the fungal hyphae (invisible threads) to send up their fruiting bodies.
The invisible parts of the fungi will always grow in a compost bin and are, needed to break down woody material. So don’t worry if fungi appear, your compost is still perfectly safe to use round your plants.

Mice: House Mice usually stay in your house but Wood Mice will sometimes take up residence in a compost bin. They are a little larger than house mice, with big eyes, a long, furry tail and are chestnut brown in colour with a white underside. They will nibble some of the things you put in your compost bin but won’t do any harm. The only problem they can cause is making stores of grains, seeds or nuts which may germinate in your compost. Usually their little heap of bird seed or cherry stones is quite obvious and you can transfer it to a freshly working compost bin.

Rats can be really destructive and may carry disease. They like a warm, undisturbed, dry spot for their nests so having a soggy compost bin and a lot of disturbance will be a deterrent. If they are a bad problem in your area you can make a floor of double thickness wire, rabbit netting and put your compost bin on top. It is quite easy to bend the wire netting up round the sides of a small composting unit and tie it firmly round the bin 30cm above the ground. A New Zealand Box is harder to protect and you will need to firmly staple wire netting in place. Even then rats will find it easy to gnaw through the wooden sides.
A few composting units are said to be rat proof, for example the Green Johanna has a thick plastic base.

Shrews: look a bit like small mice but they have short tails and very pointy noses. They eat insects and other invertebrates and, apart from eating the odd worm, won’t do any damage.

Slugs: will eat decaying vegetation and help the composting process along but you don’t want to add them to your veg patch. Keep your compost bin as hot as possible to deter them. They tend to live under a lid or plastic cover and are easy to pick off and dispose of.

Voles: also look a bit like mice. They have a short tail, small ears and are wider and
flatter looking than a mouse. They are usually dark chestnut brown. They eat vegetation and love to make tunnels through grass mowings that are not very wet. They will nibble a spiral tunnel round the outer edge of a Compostabin if the contents are a bit dry. To deter them, keep the bin on the wet side and create a lot of disturbance by adding, emptying or turning.

Wasps: also like a dry, warm and peaceful place to build their nests. Keep your bin on
 the wet side by adding water in the spring when the queen wasps are looking for somewhere to build. As soon as you see the beginnings of a nest, break it up or, at night, puff in wasp killer. If you are allergic to wasp stings, get someone else to help but don’t ignore the wasp nest – it will only get bigger.

Woodlice: like a very damp place to rest so keeping your bin a bit dry will deter them. They don’t like fresh, green material, preferring rotting woody stuff. They don’t really cause trouble but if you have a very large population in a bin you may need to empty the bin to break up their habitat.

Having the correct balance of green and brown material and emptying or turning your compost bin at least once a year will help prevent invasions.

Dealing with these unwelcome guests is easier than you’d think.

Other seasonal tips you might find useful:
Recycle your Christmas decorations and use them in the garden.
Composting in the snow
Warm up your compost in the spring
Using your compost - make the most of your composting efforts
Use your compost in spring
Making your own compost mixes
Dealing with the Autumn Clearing - shredding and more
Is your compost slimy and smelly? - solve the problem.
Restarting your home compost bin in the spring.
Making the most of your compost bin in summer.
Composting in autumn means dealing with heaps of leaves and piles of prunings
Winter Composting - What to do when your home compost bin is working too slowly
Solve the problem of a cold, stuck compost bin.
Make your own liquid feeds from comfrey and nettles
Composting lawn clippings that have been treated with herbicide
Composting in a Bag - how to get rid of kitchen waste and revive spent compost
How to compost sawdust, wood shavings and bark