Millipedes
Diplopoda
Slow, cylindrical, many-legged recyclers that eat decaying matter. Two legs per segment means millipede; one pair means centipede, and that one is a friend.
How to know it
A hard, cylindrical, slow-moving animal 20–40 mm long, gray-black or brown, that coils into a flat spiral when disturbed. Count the legs on a segment: a millipede has two pairs per segment and a centipede one. A centipede is flattened, fast and predatory — a garden ally — and telling them apart is worth ten seconds.
What you'll see
- Millipedes coiled up under pots, stones, mulch and in the compost heap.
- Shallow grazing enlarging an existing slug hole or a rot in a potato or strawberry.
- Feeding in a tuber already damaged by slugs or wireworm, which is what gets them blamed.
- Seedlings occasionally grazed in a very damp seedbed.
- Crowds of them migrating across paths and into houses after heavy autumn rain.
Where it comes from
They feed on decaying leaves and wood and are a major part of how a garden turns litter into soil. Eggs are laid in the soil, the young hatch with a few segments and add more with each molt, and they live for several years. They need constant damp and die quickly in dry conditions.
Damp, heavily mulched, organic-rich soil, compost heaps and leaf litter. Wet autumns bring the mass movements that end up on doorsteps.
Dealing with it
- Find the real culprit first — slug, wireworm or rot — since the millipede almost always arrives second.
- Lift strawberries and melons off damp soil.
- Reduce damp cover immediately around seedlings and young plants.
- Sweep them out of the house rather than spraying; they are harmless indoors and die within a day or two.
- Leave them in the compost heap, where they are doing exactly what you want.
Keeping it out
- Keep mulch clear of stems and thin it where slugs and millipedes are both heavy.
- Improve drainage in permanently wet corners.
- Seal gaps at door thresholds before the autumn rains.
- Deal with the slug and wireworm damage, which is what opens the door.
- Learn the centipede, and leave it alone; it is eating your slugs and cutworms.
What it goes for
Decaying matter first. Potatoes, strawberries and seedlings only where something has already damaged them.
Who hunts it for you
- CentipedesChilopoda Flat, fast, one pair of legs to a segment — and a predator, unlike the slow round millipede it is constantly confused with. It hunts slugs, cutworms, springtails and woodlice by night under mulch and stones. Learn the difference and leave this one alone.
- HedgehogErinaceus europaeus A European animal, and worth saying so plainly: there are no hedgehogs in North America, and the ally that does the same night shift here is the toad, the opossum or the ground beetle. Where they do occur, cut a gap in the fence and skip the pellets.
- Salamanders & newtsCaudata Damp-loving hunters of slugs, worms, woodlice and beetle larvae that spend the day under a log or a stone and work the beds at night. Companions to the toads: they want the same damp shade, the same log pile, and the same absence of slug pellets.
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com