there are several different species of worms and they do tie them selves up 'in knots'. when the weather changes considerably they also change their behaviour. Don't worry about them. have you fed the lawn recently? that will add chemicals that may irritate the worms and may be the cause of the colour change if its not the species difference. does that make sense?

The only yellow worms that spring to mind are Mealworms, favoured by fishermen. They are not a worm as such but are a larvae of the Mealworm beetle.

I'm not quite sure what you mean by "knotted up" though as larvae haven't the ability to wrap around themselves. Their body has very distinctive rings around them, is this what you mean?

worms coil them selves up like a knotted elastic band Myron. I used to be fascinated by them when I was little.

Worms are fascinating - in the years I've been gardening, I've found them knotted up, coiled, stretched out, and in different sizes and colours, ranging from brownish red right through to pale yellowish beige.
It would be interesting to know where you're finding these worms and whether you've recently applied any chemicals to the garden.

Yellowish sounds suspiciously like wireworms--actually a pesky beetle larva. Are they somewhat hard-shelled and glossy, Pn59ebf?

norman
thanks all for your answers,the only thing put on the ground is growmore and horse manure

Now that you've mentioned horse manure, could they be equine roundworm? They certainly fit the description but I'm not sure if they would live outside the animal for long.

this is a natural behaviour for our native earthworms. there are many different species in Britain. gut roundworms tend to be white/beige.