Who’s who in slugs
Slugs have a PR crisis in the gardening world. But do they really deserve the bad rep? RHS entomologist Hayley Jones sheds light on the little-known benefits slugs bring to ecosystems
It’s probably safe to say that most gardeners, wearied by the memories of munched courgettes or vanished seedlings, don’t view slugs with the same fondness as some other garden wildlife.
However, slugs play valuable roles in our gardens and ecosystems, and the number of slugs that are ‘pest species’ on our garden plants is actually low in proportion to the wide array of fascinating slugs found in the UK. RHS entomologist Dr Hayley Jones is here to introduce us to who’s who and what they do.
The plant munchers
These are slugs that do really like the taste of your prized hostas, young lettuces and other leafy treats around your garden. However, it’s important to remember that there is no effective or sustainable way to get rid of slugs and the best approach is to encourage a healthy and balanced ecosystem in your garden that promotes natural predators, tolerate some level of damage, and reduce risk to vulnerable plants where possible, such as by raising
Deroceras reticulatum
Grey field slug
Key features:
- Dark fishnet pattern on tail/sides
- Small and usually pale buff with dark flecks
- Body contracts to a swollen hump
Tramp slug
Key features:
- Paler ring around breathing pore
- Tiny black flecks on brownish body
- Mantle (smooth, saddle-shaped area between head and tail) usually has a pale centre
Deroceras invadens
Arion ater
Large black slug
Key features:
- Medium to very large slug
- Variable colour from yellow to black
- Contracts into a hump and squirms from side to side when disturbed
The good guys
Gardeners may have traditionally viewed slugs as the enemy, but we are now beginning to understand just how important they are in the garden ecosystem.
Most slugs are great garden recyclers, grazing on algae, fungi and detritus. Many species feed on decomposing organic matter, such as dead leaves, dung, and even dead animals. They are beneficial animals to have in a garden as they are a valuable part of the
The leopard slug, which in itself doesn’t pose a threat to your plants, is highly territorial and actually scares off other slugs – a guard slug! So, slugs can in fact be a gardener’s friend.
Green cellar slug
Key features:
- Medium to large slug
- Mottled with greenish blotches
- Plump body and tail
Limacus maculatus
Testacella scutulum
Orange or golden shelled slug
Key features:
- Golden-yellow speckled body with bright golden yellow underside
- Small flattened shell near the tail
- Slow-moving and dry to the touch
The cool ones
Slugs are far from boring, and some bring really interesting features to the table. The ash black slug, a woodland specialist, can grow up to 30cm long and can be an indicator of ancient woodland. The native shelled slug does indeed have a shell (yet is not a snail), lives almost entirely underground, and is carnivorous, feeding on worms.
The tree slug feeds on algae and lichen at the tops of trees – it can be seen gliding up the tree in the evening looking well hydrated, and coming back down again in the morning looking distinctively shrivelled after a hard night’s cleaning.
