Small heaps of soil on a lawn raise an immediate question: mole, vole or something else? Three pages from the Royal Horticultural Society (RHS), each read on 2 November 2026 and each undated, answer parts of it: its advice guides on moles, on mice and voles, and on earthworms. This article sets them side by side, for gardens in Britain, as general information.
Which animal leaves which mark?
| Sign | What the RHS says |
|---|---|
| Molehills | Heaps of excavated soil thrown up on lawns and flower beds; moles are rarely seen because they live mostly underground |
| Soft lawn with small soil heaps | Likely to be voles tunnelling just beneath the surface, as opposed to moles; the tunnel networks can leave a lawn uneven and soft |
| Worm casts | Soil and undigested material excreted by worms as they feed; mainly produced by earthworm species that live in permanent burrows |
The RHS adds that in many cases the molehills seen in a garden are the work of just one mole, because moles are very territorial. Mole activity is usually greatest in late winter and early spring.
What each one eats
The RHS describes moles as carnivorous. They feed on invertebrates that fall into their tunnels, mainly earthworms and other soil-dwelling creatures, and do not feed on plant roots. It says any plant damage is incidental to their lifestyle, although tunnelling can disturb the roots of seedlings and other small plants in flower beds and vegetable plots.
Mice and voles are different. The RHS says they can feed on a wide range of plants, and that both leave paired grooves where their incisor teeth have gnawed stems, crocus corms and stored apples. It lists holes in the soil where they have dug for bulbs, corms or germinating seeds, and says voles sometimes eat the bark of woody plants, particularly in winter. Crocus corms and tulip bulbs are often eaten, especially in the first autumn and winter after planting, while established bulbs and corms are less susceptible.
Earthworms are different again. The RHS says they eat decaying plant material and do not damage growing plants, and that they are important to soil structure and fertility. It also says there is no need to introduce them, because they are usually present at natural densities and will colonise new gardens.
Telling a mouse from a vole
For anyone who sees the animal itself, the RHS gives two clues. Mice differ from voles in having tails that are longer than their bodies. Seen from the side, a vole’s head has a rounded appearance, whereas a mouse’s head extends forwards. The RHS names the wood mouse, the short-tailed vole and the bank vole as species often found in British gardens, plus the yellow-necked field mouse, which it says mainly occurs in southern England and Wales.
What does the RHS suggest doing?
For moles, the RHS says that where possible they should be treated as part of the biodiversity that gardens support. It says molehills on lawns can be removed before mowing, and collapsed surface tunnels filled to keep the surface level. If a mole is considered too disruptive, it lists steps that mitigate its activity, encourage it to move elsewhere, or control it.
For mice and voles, it says they are normally present at low numbers and can be treated as part of the biodiversity that gardens support. When numbers are high and damage is intolerable, it says it can be difficult to make much impression on them, and that they do not sustain high populations for long. It suggests tree spirals on young or newly planted trees to reduce bark damage and, where possible, tolerating the animals or using barriers and contained storage, because all methods of control involve killing them. It points readers to the RSPCA’s Living with series for more on living with mice.
For earthworms, the page describes casts and the animals’ role in soil, and contains no suggestion to control them.
How the RHS words its deterrent advice
The mole page is careful in how it describes products and plants:
- Mole netting can prevent moles reaching the surface, but it must be installed before turf is laid and is usually plastic.
- Electronic devices produce a buzzing noise that is “said to” drive moles away, but the RHS says this may only be to another part of the garden.
- A mole-repellent smoke is said to deter worms and other food from the tunnels; the RHS says the mole may move elsewhere or simply create new tunnels nearby.
- Caper spurge has adherents who claim its root exudates repel moles, with a warning to remove most flower heads before seeding or the plant can become invasive.
- Bulbs of Allium moly are sold as a mole deterrent but the RHS calls them of doubtful value.
Those are the RHS’s own cautions, not test results, and none of the three pages gives a success rate for any method.
The bottom line
The RHS pages describe three different causes of lawn heaps: molehills, soft areas with small soil heaps attributed to voles, and worm casts. They differ in diet. Moles eat invertebrates rather than plants, mice and voles eat plant material including bulbs and bark, and earthworms eat decaying plant material. For moles and for mice and voles the RHS says to treat them as part of garden biodiversity where possible, and its deterrent advice is hedged. The pages say nothing on treatment under any particular law or on hiring contractors.
Sources
- Moles in Your Garden, RHS Advice, page undated, read 2 November 2026 (rhs.org.uk)
- Mice and voles: Identification & Control, RHS Advice, page undated, read 2 November 2026 (rhs.org.uk)
- Earthworms, RHS Advice, page undated, read 2 November 2026 (rhs.org.uk)