Earthworms

Many insects have an other-worldly look, an alien appearance that might be more alarming were they to get any larger; earthworms are no exception. Though they tend to be lumped into the same category, they’re not actually insects at all; they’re detritivores, and detritivores are to gardeners what dogs are to man: best friends. They feed on decaying matter, which is beneficial itself, but worms are so much more than just waste disposal machines; they mix the soil up, aerating it, allowing water and oxygen to flow better through it, secrete many nutrients in their own waste matter, all the while, providing a tasty meal for birds, foxes, frogs and moles, and many other garden visitors. All hail the humble earthworm!

As with most creatures, there are several varieties of earthworm found in the UK – around 31 – but only 16 or so species will usually be present in our gardens, falling into 3 categories: 

Anecic worms
These little miracle workers are the most common here in the UK. The largest species, they’re reddish-brown in colour and feed on fallen leaves that they drag into their permanent, vertical burrows. They’re also responsible for middens – piles of casts – often visible on lawns, and whilst those casts may be a source of irritation, they’re a sure sign of healthy soil.

Endogeic worms
Like anecic worms, endogeic worms live in soil, but unlike their cousins, they eat the soil, aerating it as they move through it. They can be blue, green, grey or pink in colour, and whilst their horizontal burrows can go very deep in the soil, they often use existing burrows.

Epigeic worms are sometimes split into 2 groups: epigeic and composter, but both groups differ from other worms because they live on the surface of the soil rather than burrowing in it. They feed on garden or kitchen waste – fallen leaves or compost matter – consuming it swiftly; they also reproduce rather quickly, providing more worms to continue the good work. They’re either bright red or reddish-brown, and those found in composts are often stripy and known as brandling or tiger worms. Whilst they naturally thrive in these little ecosystems, when starting new compost heaps, gardeners sometimes add these worms to speed up the process, a practice known as vermicomposting.

Whatever category they fall into, earthworms are generally prevalent in all gardens, and although a high number could mean more casts, never have the words, ‘the more, the merrier’ been more apt: the more worms present in your garden, the healthier it is; conversely, a lack of worms suggests a problem, and that could mean overly-acidic or waterlogged soil. Earthworms are generally less active during cold or hot and dry weather, so bear that in mind, and some feed at night so may not be so obvious during the day.

Worm casts will inform you of the prevalence of worms. They’re small piles of what look like lumps of mud but are essentially worm faeces containing undigested matter that bacteria and fungi feed on; this releases valuable nutrients that benefit the soil. Casts may contain as much as 5 times more nitrogen, 7 times more phosphorus and 1000 times more beneficial bacteria than the soil they originated from. Whilst they may look unsightly, casts – generally only visible from autumn to spring – are easily dispersed when they’re dry, and their existence e is arguably more of a pro than a con.

And then there are the burrows created by worms. Yes, they create a natural ventilation system whilst also producing excellent drainage, but they’re also lined with bacteria, the remains of organic worm meals and anything the worms have dragged down into their burrows, all glued together with secreted worm mucus, and this mixture releases nutrients that not only promote healthy soil, they’re consumed by plants too. Moving through the burrows mixes the soil whilst integrating organic matter into it, creating further nutrients for bacteria, fungi, plants and the soil, improving soil fertility.

Contaminated soil can also be helped by the presence of earthworms. They have the ability to blend lead and zinc with phosphorus and zinc, excreting tiny pellets containing the metals that are insoluble and non-hazardous to the soil. Worms living in soil with high toxicity levels have also evolved to absorb more contaminants than the average worm, and although they do release carbon dioxide from the soil, research shows they capture more than they release; they’re truly unwitting eco-warriors!

With a diet of soil and decaying garden matter, worms can consume their entire body weight in a single day; what you put on your lawn, plants and soil, then, will have an impact on the earthworms in your garden. The use of toxic pesticides can harm their health, fertility, they’re ability to function, and in extreme cases, kill them. Dead worms will mean unhealthy soil, and unhealthy soil means unhealthy plants; be kind to your worms, and they’ll be kind to you!

Although they’re hermaphrodites, worms still need other worms to reproduce; contrary to popular belief, cutting worms in half does not create new ones, it just harms or kills them, so please don’t try, and allow them to create new worms themselves. 

Extremely acidic soils aside, worms will be innocently improving everything about the earth around them, and it’s the mucus covering their bodies that aids smooth movement even through the heaviest of soils. Their muscles contract to assist forward motion, and retractable bristles on their bodies help them grip and move faster. With no eyes, they sense light and soil vibrations which guide them in the right direction, generally away from the sun to avoid drying out; they have no lungs either, breathing through their skin instead, but problems arise when there’s heavy rain, and you’ll often find earthworms at the surface of the soil when it rains to avoid drowning.

Charles Darwin claimed worms were the most important animal that ever existed because their movements are so beneficial to soil and thus, everything that relies on it; he stated: “It may be doubted whether there are many other animals which have played so important a part in the history of the world as have these lowly organised creatures.” – praise indeed!. His book, The Formation of Vegetable Mould Through the Action of Worms, published in 1881, outsold On the Origin of the Species when first released, so worms were a big deal in the late 19th century. Nearly 150 years later, maybe it’s time to give these wiggly wonders back their metaphorical crowns and offer them a little more respect. A few less chemicals, a little more garden waste, a compost heap, even, containing a lot of vegetable matter, and they’d be happy! A happy worm means healthy soil, and healthy soil means a happy gardener; isn’t that what we all want?