Millipedes: harmless recyclers (mostly)

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Slow, many-legged, and quick to curl into a neat spiral when you disturb them — millipedes are a common sight in damp, mulchy raised beds. Good news: they're firmly on your side.

What they actually do

Like slaters, millipedes are decomposers. They munch through dead leaves and organic matter, turning it into humus that feeds your plants. They simply don't have the jaws to attack a healthy, growing plant.

The catch

Two small things. In very high numbers they'll occasionally rasp at seedlings or soft fallen fruit. And in southern Australia the introduced Portuguese millipede (glossy black) can swarm into houses in autumn — a genuine nuisance, but still not a threat to your veggies. Don't confuse millipedes with centipedes, either: centipedes are faster, flatter and have one pair of legs per segment. They can nip, but they're predators that eat pests, so they're friends too.

What to do

Leave them be. If numbers explode, it's a sign the bed is very wet and very rich — ease off the watering and let the mix dry a little between drinks, and they'll settle.

Not sure whether the bug you've spotted is friend or foe? Our Garden Trouble Calendar shows the pests and diseases that are actually active in your area right now — everything else is usually one of the good guys.

Image: KIRUTHIKA OFF, CC BY-SA 4.0, via Wikimedia Commons.