Smooth barriers can stop millipedes from entering houses because they cannot cross smooth, vertical or rounded surfaces. These can be fixed to walls, below doorsteps, window ledges and vent bricks but must be kept clean and free of bridging vegetation. These barriers must be continuous with no breaks, unless placed under doorways.
Plate glass, 7.5cm wide and 4.5mm thick, can be set around the base of the house. This prevents millipedes from entering because they cannot gain a foothold on the smooth surface.
A moat and trap system can also be installed around dwellings. A 100mm C–Purlin with return lip, buried flush with the surface of the ground may be used for this. Millipedes fall into the moat (wet or dry), and cannot escape the overhanging sides. The ends of the channel may also be modified to include a trap, but this is not necessary as the millipedes will die in the moat if it is clean and free of debris for them to feed on or dwell in.
A less permanent barrier is formed using a wide smooth vinyl, polypropylene or polythene tape of at least 48mm. Teflon-coated tape can also be purchased. Fix the tape to the wall with contact adhesive.
Light-traps have offered good control. You can purchase light traps, some with solar powered lights, from your retailer or online. Alternatively you may choose to construct your own light trap using a trap box with smooth sides, buried flush with the surface of the ground and using low voltage garden lights or a weather-proof fluorescent light to attract the millipedes at night. If the trap box sides are smooth and at least 100mm high, the millipedes will fall into the box and not be able to escape. Light traps can be set up along the outside wall near where the millipedes are entering, or in the garden to lure them away from the house.
Residual chemical barriers at least one metre wide present millipedes with a treated surface wide enough to kill them before they enter a house. Many pesticides have a limited active life and must be re-applied for ongoing control — especially during periods of rain.
Chemicals can be applied to outside walls, paths and garden beds or other areas where millipedes are thought to breed.
Chemicals must be used in accordance with instructions on the label.