Compost heaps and wildlife

by Kate Bradbury

It's remarkable how much life a compost bin can attract...

Worms on compostLast week I wrote about the wood mouse that has taken up residence in my compost bin. So far I have resisted urges to check up on it, but have enjoyed the odd fleeting glimpse as I've added fresh waste to the bin.

With the new resident fresh in my mind, I seem more aware of the other inhabitants of my compost heap. Last Sunday I noticed some sort of eggs had been laid on the underside of the lid; further down there was an ants’ nest, while masses of worms, rove beetles and woodlice writhed in the waste below.

It's remarkable how much life a compost bin can attract. Books will tell you that a compost heap is one of the best garden features to attract wildlife but, somehow, this 'life' inside the bin can go unnoticed.

We gardeners normally only concern ourselves with the slugs that eat our plants. But look inside your compost bin and you might find their yellow cousins, Limax flavus. Yellow slugs are a gardener’s friend, as they feed almost exclusively on decaying matter. I have only once seen them outside the bin and that was when they arrived. When I moved house I brought my compost heap with me, and one rainy evening I watched two fat, yellow slugs slither down the wall to move into their new home.

A couple of weeks ago I watched a hoverfly, Myathropa florea, laying eggs inside the bin. Another one was buzzing about on Sunday, trying to find a way to the waste inside. The larvae of many hoverfly species eat aphids, but not these. The ‘rat tailed maggots’ are happier living in decaying matter, before they pupate and emerge as beautiful adults.

Whatever is attracted to compost must be lured there by its smell. Mine is a small, wooden bin, so the waste inside can dry out quickly and often breaks down anaerobically. Because of the bin’s faults and size, I have to empty it regularly to aerate the contents so it breaks down quicker. Every time I do this a pile of semi-rotted waste ends up on the lawn and, within minutes, insects have flocked to the garden.

Dung flies are the first to arrive – they gather to mate on the heap. Then hoverflies turn up to lay eggs on it. Once, a common blue butterfly spent the night on a particularly smelly mound of semi-rotted compost. What powerful antennae these creatures must have...

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Gardeners' World Web User 25/08/2011 at 16:18

One of my "Green Daleks" - plastic composters really - is home to a whole family of slow worms, Kate. They are very beautiful. I was just this morning showing another volunteer at the Botanic Garden the good slugs, which were out in force today after last night's downpours.

Gardeners' World Web User 25/08/2011 at 18:36

I've only just read your lovely blog, but I too made an entry about hoverflies and their larvae as they are all over the wood I survey. Great minds eh?

Gardeners' World Web User 25/08/2011 at 18:58

I am just about to purchase another compost bin as mine is full and I am having to take my pressuos cuttings down to the tip, I know they recycle the waste and make compost of it, I wouldn't like to buy it though as people put in deseased garden waste.

Gardeners' World Web User 26/08/2011 at 07:43

Crumbs, I have learnt something about yellow slugs today, in future I shall give those a reprieve from my edging iron or dutch hoe. But I do wish someone would tell me how to stop those horrible tiny flies that inhabit my bins. They swarm up in my face as soon as I lift the lids or disturb the contents. What are they and what do they do?

Gardeners' World Web User 26/08/2011 at 09:09

One of my compost heaps is untouchable - honey bees have made it their home. I rang the local bee keepers who warned me not to touch until the end of September. I have put wire netting over it in case enthusiastic grandchildren give it a poke!

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