What’s under that pot?

What's under that pot? © Rowena Millar

This morning I did a bit of garden exploration, and it’s a mini-jungle out there. Why not give it a go yourself, either by yourself or with children, and we can compare notes and find out more.

I looked under the movable pots in and around our greenhouse, and here’s what I found:


Woodlouse © Rowena Millar

Woodlouse © Rowena Millar

The common minibeast I found pretty much everywhere was the woodlouse – grey and in its own armour, a little bit like a tiny garden armadillo. The one pictured is probably the common rough woodlouse (Porcellio scaber) but I’m pretty sure we also have the common shiny woodlouse (Oniscus asellus) and possibly others, too. There are 45 species in the UK, five of which are common.

Woodlice are crustaceans like lobsters, crabs and shrimps. You can find their relatives, such as the sea slater, on the beach. A sign that our garden woodlice have watery origins is that they breathe through adapted gills which, unusually, are located on modified hind legs. The oxygen diffuses through water, which is why woodlice are found in damp places. However, their armour isn’t waterproof and they drown if they fall into a watering can of water.

I don’t bother clearing woodlice out of the greenhouse. There are many of them, but in my experience they don’t damage healthy plant tissue except possibly the very softest of all, like a sappy new seedling or a squashy strawberry.


Slugs © Rowena Millar

Slugs © Rowena Millar

The second-most abundant creature I found was the slug – I think they were (unfortunately) the netted or grey field slug (Deroceras reticulatum), which is bad news for my seedlings. Some of the other, larger, slugs are happy to dine on rotting plant matter or even on smaller slugs, but these blobby looking (while sheltering under pots) little field slugs are best kept away from tender young plants.

If you need to catch these plant-eating slugs, check under pots or find them by torchlight in the evenings. Don’t poison them, or you’ll poison their predators too. Instead, place them somewhere where they can eat less precious plants and become food for your garden frogs, toads, hedgehogs, ground beetles, garden birds and in my case, highly voracious ducks!


Centipede © Rowena Millar

Centipede © Rowena Millar

I was surprised to find several centipedes under my pots, as well as under stones and paving slabs. Centipedes are quick to run away or burrow, but I managed to get a photograph. These fast-moving predatory ‘earth centipedes’ might help eat those small slugs.

The centipedes I found were probably the western yellow centipede (Stigmatogaster subterranean, also known as Haplophilus subterraneus), the longest centipede in the UK and widespread in southern Britain – but there are several similar species. If you find a larger, darker, armoured looking centipede with 15 pairs of legs, it might be the brown centipede (Lithobius forficatus).

Note that millipedes are generally less flat than centipedes and move more slowly. They can curl up, and their many tiny legs (two pairs per body segment) are underneath rather than sticking out at the side. Millipedes eat decaying plant matter.

Glass snails

I think the little snails I found were glass snails – possibly the cellar glass-snail (Oxychilus cellarius). To my surprise, when I looked up cellar glass snails online I found that they eat almost everything they can find, including other slugs and snails and their eggs, insects, worms, faeces, dead animals, and live and dead plants. I had absolutely no idea!

Compare the shape and colours of the shell to the other snails you find around your garden and pond. They are incredibly varied in shapes, sizes, patterns and colours, and addictively interesting once you start looking closely.

Australian flatworm

Australian flatworm © Rowena Millar

Australian flatworm © Rowena Millar

Another surprise – a creature from ‘down under’ that shouldn’t be here at all. Australian flatworm (Australoplana sanguinea) is a small, pinkish-orange flattened planarian (flat) worm that is a gruesome predator of our native earthworms. The first record dates back to 1980 on the Isles of Scilly, and they are now widespread in South West England. Seek them out under flat paving slabs and stones as well as under flat-bottomed pots. There were several in my greenhouse! Although these are ancient creatures, and the way they wave their pointed front ends around endearingly and stretch from a wrinkled blob to a long, shiny thin ribbon is all rather interesting, they come from afar and their natural predators are not present. For the sake of earthworms, you might perhaps want to catch them and seal them away in a dry jar, where they don’t last long.

Note that we have 14 British land flatworms and water flatworms too. None of these look like the pinky-orange Australian invasive one, though. Find out more about the four main invasive land flatworms and the PotWatch survey run by the charity Buglife.

Garden symphylid

Garden symphylid © Rowena Millar

Garden symphylid © Rowena Millar

I didn’t know what the very miniature white centipede-like creature I found under the final pot was, but I think it’s a garden symphylan or symphylid – a very small white creature with antennae. Unlike a centipede or a predatory beetle, it eats organic matter and so it doesn’t need to move around so quickly. Apparently, symphylids travel through soil in the former burrows of worms or other tunnellers in heavy or rich, moist soil. Who knew?

So these are the creatures living under my pots. What’s under yours? Let us know via the Cornwall Wildlife Trust Facebook page.

If you think I’ve misidentified any of my little garden creatures, just let me know. There’s so much for each of us to discover, right under our noses – and under our pots.