Happy World Earthworm Day! Yes, Friday 21st October 2022 is a day of celebration for all things earth-wormy!

Did you know, Britain has about 16 species of earthworm that are likely to be found in gardens, but there are nearly 30 in total that might be found in the UK? As you probably have noticed, they vary in size and colour, but they all help to create soil structure and fertility.

Composting worms are not the same as the common garden worms that we might find when digging a bed. When it is cold, composting worms burrow down and make a ball, almost hibernating to conserve energy. They behave in a similar way when it is really hot, burrowing down, but also cover themselves with slime to stop themselves drying out. Common compost worms are called brandling worm (or tiger worm), dendras, or red wiggler and they like temperatures between 15C and 25C ish.

There is actually an earthworm society! www.earthwormsoc.org.uk/ Worms are divided into four groups depending on where they like to live in the ground. Some like to have deep vertical burrows – up to 2m deep perhaps – and these ones can be up to 40cm long. Some like to have burrows much nearer the surface and horizontal. A third category likes to hide under logs, leaves, moss or rocks – and don’t burrow at all. And the fourth group is composting worms.

Earthworms have tiny bristles which help them move along. Eight bristles per segment! They are hermaphrodite, which means that they have both male and female parts. But they do have to find another worm in order to reproduce. When they do, both worms are then fertilised by each other.

Ever wondered about the funny wider part about a third of the way down? In adult worms the ‘saddle’ can be seen – this is a ring covering several segments about a third of the way down the worm’s body. Inside is where egg cocoons are made. Worms without it are probably young worms.

Did you know Darwin studied earthworms? He wrote a paper about them the year after he came back from his famous Beagle voyage. And, at the end of his life, he wrote a book about soil through the action of worms – which sold out eight times in a year – and was actually a more popular book in his lifetime than “On the origin of Species”. He honestly never expected the public to be interested! His studies, over about 40 years, included looking at how worms take leaves down into their burrows – whether they prefer to take the tip of the leaf in first (yes, mostly) or the side, or the stalk of the leaf. He carried on with paper triangles to see if they like the tip, or the base, or the middle edge of the triangle. Other studies he did looked at how fast rocks appear to “sink” because worms (with their worm casts) bring soil up to the surface.

Did you also know that there is an annual worm charming competition? People are given a square meter and they have 30 minutes to charm as many worms out as possible, without digging, chemical or water. The record is more than 500!

Farmers are being encouraged to count earthworms in test pits as an indicator of the soil health. Worm casts are a joyful sign to farmers and growers! If you dig two holes in a field, you might find earthworms in the soil from one but not in the other. Below is a YouTube video link to watch on the topic of earthworms showing soil health.

Find out in this video (https://www.youtube.com/watch?v=WaqI_RUrfzM – 53 mins) about what factors might control for earthworms in a hole and how many holes we should dig to find one! The AHDB (Agriculture and Horticulture Development Board) has a helpful earthworm recording sheet to help. https://ahdb.org.uk/knowledge-library/how-to-count-earthworms

If you would like to know more about worms there is a webinar on 2nd February 2023 and another two in March. Find the events on the entoLIVE eventbrite page www.eventbrite.co.uk/o/entolive-35982868173 – enjoy!

Here is some other YouTube videos about discovering earthworms:

Exploring earthworm ecology (1 hour long) https://www.youtube.com/watch?v=q7Eznl12V_g – find out more about the four groups that worms are put into and other features about their colours and how to recognise them.

Earthworm research that Charles Darwin undertook (1 hour 6 mins) https://www.youtube.com/watch?v=nKeJj_aXeTw really fascinating studies that Darwin did – at the time his systematic way of recording data would have been completely novel – and the book he wrote which combined biology, behavioural observations and many other modern science disciplines together.