Lawn care is often a precise and careful balance of watering, feeding, mowing and raking, and it can seem like even the slightest mistake can quickly undo all your hard work. If you start to find random piles of soil in your lawn, it's likely a wildlife creature trying to take over your grass.
Moles are one of the most common critters that dig into lawns. They create distinctive round mounds of dirt with a hole in the very centre at the top. Molehills are commonly 15 to 20 cm (6 to 8 inches) wide and are perfectly circular and symmetrical, sort of like giant anthills. The mounds form as the moles tunnel under your lawn until they reach a certain point, and then they dig up and out, creating the mounds and holes. They will enter and leave their home repeatedly by the same hole.
Gopher mounds are similar to molehills and are created in much the same way. However, gopher mounds tend to be more raindrop-shaped as opposed to perfectly circular and symmetrical. They are also bigger than molehills, sometimes measuring 37.5 cm (15 inches) across. However, as gophers are not native to the UK they are unlikey to be the pests in your lawn -- unless the broke out of a nearby zoo.
Earthworms create very small piles of soil, often only 2/5 to 5 cm (1 to 2 inches) tall. These piles are formed when the earthworm digs through the soil in your lawn; the worm actually passes the soil through its system and sends it back out the other end. While this seems pretty disgusting, the soil itself is virtually unchanged from its original form; it's simply built up into small piles to show where the earthworm has passed. There will not be holes visible on the top of these small mounds, but if you move away the soil there will be a small hole underneath through which the earthworm disappeared.
Larger mammals like moles often invade your lawn to feed on other lawn pests such as the earthworms or grubs, which feed on grassroots. The best way to get rid of any of these mounding problems is to treat the lawn for grubs and worms. There are a variety of products available on the market to treat worms and grubs in the lawn, and their uses depend on the type of grass you have, the time of season and the type of insect you are treating. If you are unsure about which product to use or how to use it, talk to a professional at a garden centre.