Size: Most British species are between 3 and 10cm but the largest species (the lobworm) can grow up to 35cm long
Description: The earthworm’s appearance is fairly distinct amongst garden critters – they are basically a long, thin, muscular tube! Colours don’t vary much between different species, with most being a shade of brown or dull pink. The length of the body is formed by a series of ringed segments. Adult worms have a thicker section closest to the head known as a clitellum which is used in reproduction to form a cocoon for its eggs.
Earthworms are slimy creatures which can be found slithering through your soil or sometimes on the surface of the lawn after a rainstorm or if feeding. They need to stay moist as this allows them to breathe through their skin, and can get into trouble if they become stranded on concrete as they dry out and die very quickly in direct sunlight. Underground, they feed on all sorts of organic matter such as fruit or plant remains and will often pick up minute organisms such as bacteria or fungi in the process. Sometimes they will come to the surface for a buffet of dead grass and fallen leaves. Many earthworms reproduce in an odd fashion, having both sets of sex organs. Many species create clones of themselves through asexual reproduction. They then form a cocoon for their offspring which incubates the embryo until it emerges as a small but fully formed worm.
Earthworms also have an incredible ability to regenerate their body if they lose any segments. This is sometimes used as a defensive tactic and you may find that if you try and pull an earthworm from the soil, it will grip on with the minute bristles that cover much of its body and the part of its body you’re holding will break off and regenerate over time. Don’t go pulling at worms though as they can only repair their bodies to a certain extent!
In the garden
Earthworms are absolutely essential and act like miniature gardeners. They have all sorts of uses and can be an indicator of a healthy garden – the more worms, the healthier the soil! They dig tunnels through the soil and secrete mucus which allows them to move freely, pushing air as they go. This helps to aerate the soil and trap moisture which provides water for the plants growing above. Even their droppings (or casts) are good for the soil. Many species come to the surface and eat dead leaves or other decomposing material which is broken down and recycled in the earthworm’s digestive system and comes out like compost, full of minerals and nutrients, which makes the soil very fertile. As well as being good for the soil, worms have the unfortunate pleasure of being an excellent, juicy meal for many garden creatures. Healthy worm populations can help sustain all sorts of birds, mammals and insects and it’s not uncommon to see birds yanking poor defenseless earthworms from the ground and gobbling them down in one! So, it is important to keep a high population of earthworms in the soil and the best way to do this is to be great hosts and provide plenty of food and a fantastic home for them. They will eat most organic matter that you put down for them so try to scatter any old food or garden waste onto the ground and they will come up and dispose of it for you. They will even eat things like wet paper but avoid feeding them any acidic or spicy foods or things like onions or garlic. It is also important to provide a good soil for the worms to live in. Remember that worms like a mild and moist environment so avoid using any chemical pesticides on your soil and try to keep moisture in the soil all year round. In the heat of the summer, it can help to have a sprinkler or a hose to spray a bit of water across your lawn. Make sure not to spray too much though as you may drown your worms!
Earthworms are so beneficial that they are sold around the world. In some countries, they are even sold as food. In New Zealand, the Maori refer to them as Noke, which is considered a delicacy. I wouldn’t recommend eating the ones you find in your garden though!