Country diary: the lair of the blue-grey worm

Matt Shardlow
Country diary: the lair of the blue-grey worm. Short Wood, Northamptonshire: Britain’s most colourful earthworm is most often seen in water-logged conditions

The wind roared through the trees last night and rain fell hard. Now, along the crest of the hill above Glapthorn village, within the shelter of Short Wood, it’s not muddy underfoot, it’s watery.

Turning logs is a common pursuit of certain natural historian types, myself included. But today the sport is marred, as rolling a mossy log merely allows a puddle to rapidly flow into the newly exposed depression.

The technique does reveal one very interesting animal: a favourite of mine, a blue-grey worm (Octolasion cyaneum). This is a substantially sized earthworm, although never as massive as a fully grown lobworm (Lumbricus terrestris). Blue-greys are most commonly observed in waterlogged conditions when, even in daylight, they will leave their shallow burrows and seek higher ground. The blue-grey is our most colourful earthworm: the pale pink head grades into a lilac body and the tip of the tail is abruptly primrose yellow – the easy diagnostic feature.

Adult worms, such as this one, also sport a peach-coloured saddle. This band contains male and female sexual organs, but there is a twist: every blue-grey worm is a clone of its parent, there is no DNA-mixing stage at all, so those sexual organs are unrequired vestiges from a long-distant ancestor.

Splashing along the ride, I spot several more blue-greys of various sizes, snaking slowly through the fallen leaves. The diversity of clone lines is exceptionally low; it is almost certain that all the blue-grey worms in the wood will be genetically identical.

The wind grows in prominence as I approach the western end of the woodland. Great gusts break on to the wood, whence they transform into packs of writhing invisible Chinese dragons that bowl through the trees, twisting the slender ash boughs and tossing the oak branches hither and thither. Then the rain comes in big drops, but not for long. It turns out to be the storm’s parting shot, as minutes later the firmament – formerly unbroken grey clouds – has transformed into blue sky, the wind drops and the low sun sparkles across the wet ground.