Why are my compost worms moving to the botton of their bin

Two compost worms

Two compost worms


my worms don't like to stay where their food is at, but like to move to bottom of the bin. The bin does not seem to be too hot and the food I give them is all fruit, vegetable scraps and coffee grounds.

What could be the reason for their behavior?


Hello, compost worms are epigeic species of earthworms (they live on the surface of the soil amongst their food) So it is an unnatural behavior for them to dig down into the bottom of their worm bin.

The worms will only move away from the upper layers of their bin when they don't feel comfortable there anymore.

There could be a couple of reasons for this to happen.

1.) There might have been a build up of acidity in the food and bedding. Citrus fruit for example should only be added in moderation to a worm bin.

2.) Sometimes there are invaders like black soldier fly maggots that might have taken over the upper parts of a worm bin and although the maggots are not physically attacking the worms they dislike the conditions that the maggots produce in the bin and usually move down towards the bottom of their bin. The result will be that the contents of the bin becomes soggy and smelly and the worms will die after a while.

I've written an article about the infestation of soldier fly maggots in worm farms and what to do about them. You will find the page at

Those are usually the main reasons why worms might move towards the bottom of their bin unless the bedding has become to hot for the worms to live in which you said is not the case in your bin.

So check out the pH level of your worm bedding and have a look if you can spot any BSF maggots.
Then either reduce the pH if it is to high using agricultural lime or get rid of the BSF maggots.

Kind regards and I hope you will get the problem sorted out.

Keep me posted!

Stephan Kloppert
Author of "How to start a profitable worm business on a shoestring budget"

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