The Book of the Earthworm

by Sally Coulthard

  ‘Wyrm’ also extended to include mythical animals – creatures sent to torment the soul, demons that lived in the underworld and terrifying serpents. The word was even used to describe dragons and dragon-like creatures, legendary animals in European folklore who terrorised villagers and devoured livestock. Even Shakespeare uses its archaic meaning in Antony and Cleopatra, when the eponymous queen refers to the poisonous asp as ‘the pretty worm of Nilus that kills and pains not’.

  The Latin name for the Common earthworm – Lumbricus terrestris – has an even stranger beginning. The origin of ‘lumbricus’ as a word used to describe an earthworm is unclear – one possibility is that it is connected to the Latin umbilicus, meaning ‘navel’ (hence ‘umbilical cord’) and an ancient belief that earthworms and intestinal worms were one and the same species.

  WHY WAS DARWIN FASCINATED WITH EARTHWORMS?

  In the last years of his life, Charles Darwin decided he wanted to write a book about earthworms. While most of his scientific colleagues thought Darwin’s new topic a little unglamorous for one of the world’s most eminent biologists, Darwin had long been fascinated by this ‘unsung creature which, in its untold millions, transformed the land’.

  It was a daring choice of subject in many ways, not least because, during the eighteenth and nineteenth centuries, earthworms were considered to be a nuisance, a troublesome garden pest that needed to be purged from the soil. François Rozier’s Complete Course of Agriculture, written in the second half of the eighteenth century, made it abundantly clear that earthworms were noxious creatures that needed eliminating by any means possible: ‘Every cultivator… knows the damage that worms do to seeds… it is thus advantageous to know the means to destroy them.’ He goes on to present a comprehensive list of ways to remove and kill earthworms, including going out in the dead of night with a lantern to collect them in silence, whacking the ground with a mallet until they surface, hammering a stake into the ground and shaking it till the worms appear, and pouring various toxic infusions on to the soil.* Farmers were also vehemently anti-earthworm, blaming them for damage to crops. Turnip farmer Henry Vagg, for example, wrote to the Hampshire Chronicle in 1788, furious about the wrigglers destroying his valuable turnip plugs: ‘The common earthworm by its working, makes ground light and hollow about the plants, in consequence of which they are liable to be injured.’ Henry went on to boast that his solution was to repeatedly roll and squash the soil down, a technique at odds with everything we now know about the harmful effects of soil compaction.

  Darwin was unperturbed, however, by growers’ disdain for the earthworm. His book, which was published in 1881, was the result of forty years’ worth of observations of the Common earthworm (Lumbricus terrestris). He called it The Formation of Vegetable Mould through the Action of Worms, with Observations on their Habits, although this was often shortened to just Worms. For such a lowly subject, the book was a hit. Even though Darwin himself described it as a ‘small book of little moment’, in its first month alone it sold 3,500 copies. Three years later nearly 9,000 copies of the book had been snapped up, more than equalling his other literary successes, including On the Origin of Species. Even Darwin was stunned by the interest in his book; in a letter to the geologist Mellard Reade, dated 8 November 1881, he enthused: ‘It has been a complete surprise to me how many persons have cared for the subject.’ In the same month, he wrote again, this time to another friend, the botanist William Thiselton-Dyer: ‘My book has been received with almost laughable enthusiasm, and 3,500 copies have been sold!!’

  One of the reasons Darwin gave for wanting to study earthworms is perhaps surprising. For a scientist, he was also deeply philosophical – in his view, it was the smallest creatures, the seemingly insignificant, that held the key to nature’s most spectacular processes. The original idea for the project, however, came from his uncle Josiah Wedgwood II (son of the English potter), who wanted Darwin to explain why the organic material he put down on his garden soil slowly disappeared over time.

  Wedgwood had a hunch it might be earthworms, but it was Darwin, and his experiments, that finally solved the mystery. He placed his now famous ‘worm stone’ on the ground – just a round wheel of stone with a central peg for measuring – and charted its slow submersion into the ground over years. Darwin realised that as earthworms moved through the soil, they deposited new soil on the surface, causing whatever is sitting on the surface – whether it’s small pebbles or vast megaliths – to slowly sink.

  Darwin was also inherently fascinated and thrilled by earthworms’ behaviour. He was one of the first scientists to suggest they might have social relationships (see Do Worms Make Friends? page 125), food preferences, aversion to bright light and sensitivity to vibrations; and he even suspected that the earthworm had some kind of basic intelligence. He watched with delight as the earthworms in his experiments selected and pulled leaves into their burrows, based on shape. More often than not, the earthworms would pull the leaf from its more pointed end, allowing it to fit more easily into the burrow. Investigating further, Darwin cut up pieces of paper into narrow isosceles triangles to see if the earthworms would grab those by their ‘sharpest’ end; again the earthworms would, in the majority of cases, tug the tiny triangles from their apex, the end most likely to fit into their burrow. Amazed, Darwin noted that: ‘If worms have a notion, however rude, of the shape of an object and of their burrows, as seems to be the case, they deserve to be called intelligent; for they then act in nearly the same manner as would a man under similar circumstances’ (see also Can You Train a Worm? page 118).

  How to help earthworms #2

  NO DIG

  ● Earthworms hate being disturbed. The endless digging and tilling of soil not only disrupts their natural behaviour (and risks chopping worms in two) but also destroys their burrows. The constant cultivation and turning over of soil also crashes through the delicate soil ecosystem – in just one handful of soil there are more living organisms than all the humans on the planet. Billions of micro-organisms such as bacteria, algae, fungi and nematodes work furiously away in a living, breathing underground community that’s home to a quarter of all life on Earth. Churning up soil is like taking a bulldozer to a rainforest, and exposes these micro-organisms to the damaging effects of UV light and dry air, destroying the balance and, in the end, making soil less fertile or productive.

  ● In general, you shouldn’t need to aerate soil – earthworms will do that for you. They’ll also drag organic matter on the soil surface down on your behalf. If you must dig, use a fork if possible. It’s also important not to compact the soil by walking over it – practical solutions such as making stepping stones, wooden walkways, raised beds, garden paths and not making overly wide beds all avoid the problem.

  CAN YOU EAT EARTHWORMS?

  Nobody loves me. I’m going into the garden to eat worms.

  Anon, early 20th century

  For the Makiritare people of Venezuela, earthworms are a lifeline. They eat two different species, Andiorrhinus kuru and Andiorrhinus motto, both of which contain large amounts of high-quality protein comparable with levels in cows’ milk and eggs. The earthworms are also packed with amino acids, fatty acids, minerals and trace elements, including generous amounts of calcium and iron (ten times more iron than soya beans).14

  To make the earthworms palatable, the Makiritare either cook them in hot, but not boiling water (60–80°C) or, for a real treat, smoke them over a wood fire. In fact, the smoked earthworms are considered such a delicacy that they command three times the price of smoked fish or meats. The Maori of New Zealand, Australian Aborigines and nomadic Papua New Guineans also traditionally incorporated earthworms into their diet.

  Looking towards the future, there is real appetite for new sources of sustainable protein. Scientists have been looking into the use of earthworms as human food and as an animal feed – farming invertebrates may be one way to assure food security over the next century and counteract the worst environmental ex
cesses of the global livestock industry. It’s currently possible to buy products such as dried earthworm or earthworm jerky as ready-to-eat snacks, or earthworm flour, which can be used as a protein-boosting ingredient in recipes or energy bars.

  Does this all mean you should go out into your garden and eat earthworms? The answer is probably no. For a start, earthworms tend to taste of what they eat. Garden earthworms taste of soil, which is why food-grade earthworms are raised on a diet of vegetable scraps, cornmeal or other non-soil staples.

  The average energy content of an earthworm is 5 calories per gram. That makes your average Common earthworm (Lumbricus terrestris) about 20 calories or the same as two Brussels sprouts.

  The second problem is that garden earthworms also contain potentially harmful parasites and bacteria so, unless you know what you’re doing in terms of purging and cooking earthworms, you could end up being rather poorly. There have been a number of cases of people getting very sick from eating ‘wild’ earthworms, either on purpose or by accident. In one clinical case from the US, for example, a sixteen-year-old girl developed a cough, a number of blood disorders, and pulmonary disease one month after eating an earthworm as a dare.15 Tests showed that the earthworm had been a carrier of Toxocara larvae, a disease-causing parasite that lives in the intestines of dogs and cats and can pass into their faeces and, ultimately, into the soil.

  But perhaps, most importantly, the earthworm is a gardener’s friend. Worms in the wild, as opposed to commercially farmed worms, perform such an important role in soil health that it seems counter-intuitive to start using them for food in the name of sustainability. It’d be like nibbling on a robin.

  WHY DO SOME PEOPLE THINK EARTHWORMS ARE DISGUSTING?

  EDIBLE, adj. Good to eat, and wholesome to digest, as a worm to a toad, a toad to a snake, a snake to a pig, a pig to a man, and a man to a worm.

  Ambrose Bierce, from ‘The Devil’s Dictionary’ in The Collected Works of Ambrose Bierce (1911)

  Many people simply can’t stomach the idea of eating annelids. Earthworm snacks are going to be a hard sell. But why should this be? During the 1990s, the London School of Tropical Medicine conducted an ambitious international survey to try to establish whether there were things that people – regardless of nationality or culture – found disgusting. While there were lots of cultural peculiarities and regional idiosyncrasies, there seemed to be a number of core things that most people, across the world, found repulsive. These were, in no particular order, bodily secretions, body parts (wounds, corpses, toenail clippings etc), decaying food, sick people and, curiously, worms.

  Psychologists believe that, because the notion of worms being disgusting is so near-universal, it must have some genetic or evolutionary basis. We may have evolved to recoil from worms as a way of avoiding certain species that do us harm, especially human gut parasites such as tapeworms. Disgust for worms may therefore be hard-wired in our brains, even though most worms are harmless. For some people, the reaction is mild – only the idea of eating earthworms is challenging – while for others, even looking at an earthworm triggers their disgust response. Small-scale societies who do eat worms may have had to overcome their initial disgust response through necessity – as time has gone on, powerful and lasting cultural values have overlaid evolutionary ones.

  EARTHWORM ‘CURES’

  And therefore, sir, as you desire to live, A day or two before your laxative, Take just three worms, nor under nor above, Because the gods unequal numbers love.

  John Dryden, ‘The Cock and the Fox’ (1700)

  Earthworms have also been an ingredient in medicines for centuries. Folk doctors in Burma and India have long used earthworms in the treatment of various illnesses, including gum disease, post-partum weakness and smallpox.16 In Iran, earthworms were baked into bread as a treatment for bladder stones, dried and eaten for jaundice, and their ashes rubbed into the scalp to encourage hair growth. In Chinese traditional medicine’s Compendium of Materia Medica, written in the sixteenth century, the earthworm is described as the ‘earth-dragon’ and also prescribed as a remedy for jaundice, as well as being used as a diuretic and means of reducing fever. It’s still used in China as a traditional remedy for convulsions and asthma.

  The ancient Roman author and naturalist Pliny the Elder recommended earthworms as a cure for dozens of ailments in his treatise Natural History. In Book XXX, Chapter 39, ‘Remedies Derived from Living Creatures’, he helpfully suggests the following:

  Earthworms are so remarkably healing for wounds recently inflicted, that it is a very general belief that by the end of seven days they will unite sinews even that have been cut as under: hence it is that it is recommended to keep them preserved in honey. Ashes of burnt earthworms, in combination with tar or Simblian honey, cauterise the indurated margins of ulcerous sores. Some persons dry earthworms in the sun, and apply them to wounds with vinegar, the application not being removed till the end of a couple of days.

  He also recommends burnt earthworms for the extraction of splintered bones, earthworms in raisin wine to expel a woman’s afterbirth, earthworms rubbed on breast abscesses, and earthworms taken in honey wine to promote lactation. Earthworms boiled in oil and injected into the ear could offer – he suggested – relief from toothache or, rubbed on rotten teeth, burnt earthworms could make them come out more easily. The humble earthworm could even, continues Pliny, remove corns from the feet, prevent varicose veins, cure kidney stones, combat jaundice, treat cellulitis and stop your hair turning white.

  Earthworms also found themselves in cures for animal ailments. One Yorkshire cure for horse distemper, for example, which appears in a 1764 edition of The Scots Magazine, includes a teacup full of earthworms tied up in a rag and boiled in ale.

  While boil-in-the-bag earthworms aren’t necessarily something to sample, the medical potential of the earthworm is just starting to be explored. Clinical studies have revealed that earthworms’ bodies contain remarkable antibacterial, antioxidative, wound-healing, anti-inflammatory, anti-tumour, liver-protecting and anti-coagulative properties.17 Such a rich range of biologically active components makes earthworms a potentially valuable source of medical treatments for the pharmaceutical industry. Problems such as cardiac or vascular diseases may, in the not too distant future, be treated with earthworm preparations. Apart from the hair restorer, looks like Pliny wasn’t too far off.

  Not everyone thought earthworms could be medicinal. In 1908, a Buffalo physician, Dr Hiram Walker, was convinced that cancer was caused by earthworms. After seven years of research, he concluded that cancer was the result of parasites that oozed out of earthworms and recommended that his patients avoid contracting the disease by giving up all vegetables.

  (Source: The Dread Disease by J.T. Patterson, 2009)

  How to help earthworms #3

  START A COMPOST HEAP

  ● Think of making compost like a recipe. Too much of one thing and the recipe won’t work, but get the ingredients balanced and it’ll give you dark, rich organic material to spread on your garden and encourage earthworms.

  ● There are two things a compost heap needs – nitrogen-rich ingredients and carbon-rich ingredients. Nitrogen-rich materials are usually lush, green or wet, like grass clippings, green leaves or vegetable peelings.

  ● Carbon-rich materials are usually drier and brown, such as cardboard or woody stems, and keep the compost nicely aerated. The ratio of green to brown ingredients should be 50:50, so for every armful of green material you’ll need to add the same amount of brown material.

  ● You can make a compost heap in a pile, in a system of bays or boxes, or in a composting bin, whichever works for your size of garden and how much space you can dedicate to the compost area.

  ● Simply add layers of green and brown material throughout the year. Stick to the 50:50 rule and you shouldn’t end up with either a sloppy, smelly mess (too much green stuff) or a dry, crispy heap that will take years to decompose (too much brown material). The wi
der the mix of materials, the better – don’t let just one or two ingredients dominate. Overleaf you’ll find a list of materials that count as either green or brown.

  ● Most people like to turn their compost regularly – i.e. once a month – to speed up decomposition. If you have an open compost heap, however, rather than a closed bin, you’ll need to consider that there may be creatures such as hedgehogs, bumblebees and toads who are using the compost heap as a nesting site. In this instance, it’s best to turn your compost just once a year, in late spring. This is the only time you can really dig around in your compost heap, turning the contents over to aerate them, without the danger of injuring any animals who might be nesting in it. Hedgehogs, for example, hibernate in compost heaps between November and late March, but also use a compost heap as a nesting site or day nest between May and October. Some people choose not to turn their compost at all – this is fine, and you’ll still end up with compost eventually, but it’ll just take longer.

  ● Having a wormery in your garden can help improve the natural levels of earthworms in your soil. Wormeries are purpose-built containers that contain a colony of compost earthworms – usually Tiger worms (Eisena fetida) or similar. The earthworms live permanently in the wormery, turning your kitchen scraps and vegetable waste into nutritious compost and liquid fertiliser for the garden. Putting the wormery compost on your garden will then, in turn, attract more wild earthworms into the soil.