Millipede Control Adelaide — Prevention Before the Swarm
They're coming. But you can stop them before they arrive.
In Adelaide, it's not a question of if millipedes will show up — it's when. Every autumn and spring, when the rain comes, thousands of Portuguese millipedes emerge from the garden and head in your house. Most pest control companies wait until they're inside, then spray. I work backwards: I help you prepare before they swarm, so you don't spend autumn vacuuming up the dead ones or dealing with that foul smell they leave behind.
I'm Werner. I run House Care Pest Control, from St Agnes, and I've been managing millipede seasons across Adelaide, mainly the north-eastern suburbs for years. No call centre, no rotating technicians — you speak to me, and I'm the one who turns up.
What you're really dealing with
The Portuguese millipede. Black, reaching 45mm long, arrived in Australia accidentally in the 1950s and spread out. With no natural predators they've thrived to what feels like plague proportions when they move.
Why they're suddenly everywhere. Millipedes live in the soil eating dead plant matter. When the rains come — autumn (March to May) and spring (September to November) — the soil gets waterlogged. So they head for higher ground, which usually means your house, your walls, under your doors where they can breathe.
The real problem, honestly. Millipedes are harmless to us, they don't bite, don't sting, and don't damage your house. But they can swarm in numbers that look apocalyptic; they smell when you squash them; and they secrete a liquid that stains your hands and clothes and can irritate your eyes if it touches them. It's their defence mechanism. It works.
Why most millipede treatments fail
Here's what I've learned so far: a sprayed perimeter might kill some millipedes and our PestShield soaking barrier is the best treatment available, but if the conditions outside your house stay perfect for them — mulch, moisture, organic matter, darkness — they still keep coming. Wave after wave. It's why one-off spraying barely dents the problem, and it's why I don't lead with chemicals. I lead with setup.
How to actually stop them — before they arrive - The non chemical approach that works
Timing matters. Millipedes start moving in late February (before the autumn rains) and again in August (before spring). If you wait until March, you're already reacting. Prep in February and August, and you're ahead.
Three things that actually work:
1. Pull back the mulch. Millipedes breed in mulch. Pull mulch back at least 30-45cm from your foundation — it's the single most effective move you can make. Keep organic debris (leaves, wood scraps, grass clippings) away from the house perimeter. This will also helps with other pests.
2. Reduce moisture at your foundation. Check your downpipes — don't allow to water pools around the base of your house, that would breed them in those great umbers. Make sure water drains away from the house. If you've got a damp patch make a better drainage system that works regardless of you having to do anything, its a lot of work but it pays out. Millipedes need moisture to thrive, and they'll move toward it.
3. Seal the obvious entry points. Cracks in the foundation, gaps under doors, gaps around pipes and cables entering the house — millipedes are tiny and they'll find them. Seal the gaps you can see. You won't succeed 100% on this, but do it anyway, stop as much as you can.
If they're already inside:
Now the funny part: inside your house its not ideal for them, and they won't breed at all, it's too dry for them. Usually they'll die within a day or two on their own. Vacuum them up or brush them out, remember the smell? So don't squash them. Don't panic about the numbers; the wave passes.
The real fix: proper drainage (and how to handle the meantime)
If you've done the prep and the mulch pullback and the sealing, and millipedes are still arriving in numbers that feel unmanageable, a perimeter treatment works — but only after you've set up the conditions against them. A spray on a foundation surrounded by mulch and organic matter is fighting uphill.
I assess your property, show you exactly where they're coming from, and advise on whether a treatment is worth it for your situation. Sometimes it is. Often, the prep work alone turns a "swarm problem" into "saw a few, swept them out."
The permanent fix is site drainage. Not just gutters and downpipes discharging 2 metres away (though that helps). Proper subsurface drainage: a French drain with perforated pipe running downslope from the foundation, or rock-filled swales graded to move water away from the house fast. I've used this in my own home in Brazil — you open a trench, run either a perforated pipe or fill it with rocks, and grade it so water flows out and away. The grass grows over it in time, and it works even under heavy rain. Once the soil drains properly, millipedes stay put. No migration trigger, no swarms.
That system is the permanent answer. Unfortunately it costs real money to do it properly, and with the high running costs of living its a real challenge.
But here's the reality: Most people can't drop $5-10k on drainage work before the autumn rains hit. So while you're planning that, a millipede treatment is an honest relief. It won't solve it on the long run, but our clients report that that's the best relief they've got and you're not vacuuming hundreds every morning. It's a bridge solution, not the destination.
Here's how I approach it: I assess your property. If drainage is the issue, we talk about the trench/pipe solution and timeline. While that's being planned or installed, a seasonal treatment during the heavy rain months gives you breathing room. Once the drainage is in, you won't need it anymore.
Some people do just the spray year after year because drainage is expensive and they manage. That's a choice. But if you're serious about not dealing with millipedes every swarm season, the drainage is the only permanent fix.
Common millipedes questions
Are millipedes dangerous?
Not at all. They don't bite, sting, or carry disease. They won't damage your house in any way. The only real hazard is the yellowish liquid they secrete — it can stain and irritate eyes if it gets in them, but it washes off with water. Harmless, just annoying in large numbers.
Why do they swarm some years and not others?
It boils down to rain and temperature. Autumn rains (March-May) and spring rains (September-November) trigger the migrations. Very wet years mean bigger swarms. Dry years mean fewer, it's seasonal and predictable.
What's that smell?
Their defence mechanism. When threatened or crushed, they release a foul odour. Don't squash them — vacuum or sweep them outside instead. No smell, no mess.
How long do they stay?
The wave usually passes in a week or two. Inside your house, they die within a day or two because it's too dry for them. In the heat of steering away from water they end up in a desert.
Can I prevent them entirely?
No — they live in every Adelaide garden. But you can reduce the problem dramatically. Mulch pullback + good drainage + sealing the obvious gaps = far fewer getting inside. Most people don't notice the few that make it through.
Do I really need a millipede treatment?
Not always. Most Adelaide homes that do the prep work manage fine with vacuuming and sealing. Treatment helps if you're in a high-swarm area or the swarms are huge, but it's not the first move — prep is. I'll tell you honestly whether your situation needs it.
When should I prep?
Late February (before autumn migration) and August (before spring migration). That's when to pull back mulch, check drainage, and seal gaps. Prepping after they arrive is too late.
Will they come back next season?
Yes. If the conditions are right (wet season, mulch, organic matter), millipedes will appear again. But if you've set up properly, the next wave will be much smaller. It's seasonal management, not a one-time fix.
Why are there so many more this year than last?
Rain. More rain means more waterlogged soil, which triggers larger migrations. Drier years have fewer swarms. It's entirely weather-dependent.
Get ahead of the swarm
Ring me on +61 457 601 995. If it's heading into late February or August, let's talk about prep before the rains come. If they're already swarming, I'll tell you if a treatment is worth it or if the wave will pass on its own.
Werner — House Care Pest Control Local, family-safe, prevention-first