Massive rainbow worm emergence

I woke up early this morning and went for a walk around the park. It was cold and it had rained a lot in the night. I had to watch my step as there were hundreds of blue-grey worms, Octolasion cyaneum, on the pavements and ground. This is a very colourful and common earthworm species, easily recognised by its yellow tail end and its orange clitellum (the central raised band) when adult. They are sluggish, live in topsoil and commonly emerge in large numbers after rain. Some individuals were the largest I've ever seen, over 26 cm! (bottom shot), although around 15 cm was much more common. I was surprised there weren't more blackbirds and thrushes feeding on this worm bonanza! Why do they come up in the rain? Reproduction can be ruled out as this species is parthenogenetic, that is, they can reproduce on their own, producing genetically identical offspring. Populations have little diversity and are made or clonal lines. Adult worms lay cocoons in the soil that contain singletons or twins.

More information
Lowe, Christopher N., and Kevin R. Butt. Life cycle traits of the parthenogenetic earthworm Octolasion cyaneum (Savigny, 1826). European Journal of Soil Biology 44.5 (2008): 541-544.

A rainbow worm

After a long overwintering period with little activity, BugBlog comes to life thanks to these active earthworms. Using my shoe as a measuring device (cropped out of the photo) and back at home I estimated that is was over 11 cm long. There were several of these worms crossing the path on a wooded patch on the university grounds, under the rain. I usually shy away from identifying worms, but the striking colour of the clitellum - the orange band towards the front of the worms called my attention. I used the Opal Identification guide Their colour, large size and yellow tail tip narrowed down to Blue-grey worm (Octolasion cyaneum), although I think rainbow worm would be more appropriate. The species is found on the topsoil on a range of habitats. This worm had some visible injuries - possibly caused by failed predation attempts by Blackbirds or Carrion Crows.

More information
Earthworm guide. Opal. here.

The log pile revisited

We made a couple of log piles in the garden last year. Today I dismantled one of them to check what was in it. This was a very 'untidy', and relatively dry log pile, with the logs having been covered on branches from pruning bushes around the garden and the location being under a large Philadelphus bush. The first finding was that a lovely crumbly pile of compost had accumulated around the logs. There was a lot of bug activity in the pile. The most abundant form of -visible- life were woodlice, especially the common rough woodlouse, Porcellio scaber, which made the compost move as they were so many, also some smooth woodlouse, Oniscus asellus and common striped woodlice Philoscia muscorum. I found three species of snails: many common garden snails, Helix aspersa (=Cornu aspersum) most of them hibernating; a yellow banded snail Cepaea (one of 5 specimens we released in the garden a couple of years ago), and several Glass Snails Oxychilus draparnaldi (photo above). Several yellow slugs Limax flavus crawled around. There were quite a few spiders, amongst then a very large Tegenaria and possibly an Amaurobius, which rapidly disappeared amongst the logs. I also found some Blunt-tailed Snake Millipede (Cylindroiulus punctatus), which coiled into a spiral when disturbed. I saw some new springtails, but I couldn't get a decent photo. As for insects, a Harlequin seemed to be hibernating on a log. By far the most shocking thing was a couple of enormous earthworms, Lumbricus terrestris, which I found while they abandoned the log pile - possibly feeling the disturbance - by creeping on the ground. One of them was so large that at first I thought it was a snake! Big fun examining this log pile, I am sure I forgot to mention some bugs. I didn't even go through the whole of it but it yielded quite a number of interesting finds.

A banded snail, some woodlice and an earthworm

Garden Snails

Three species of woodlouse can be seen in the image

A specimen of the millipede Cilindroiulus punctatus

The largest earthworm I've seen in my garden, creeping on the ground

The same earthworm being held, just for scale

A yellow slug, Limax flavus