Millipedes are common soil-dwelling creatures that are mostly harmless to plants.
Plants affected
Potato tubers, bulbs, strawberry fruits and seedlings are sometimes damaged.
Symptoms
Millipedes are seen,
sometimes in large numbers, feeding in damaged or decaying tissues on
plants. They are often enlarging damage that has been initiated
by other pests, especially slugs.
Biology
Millipedes have elongate bodies with two pairs of legs on each body segment. They may be black, brownish or creamy white in colour. Adult millipedes can be up to 40mm, but many are smaller. The most damaging to plants is often the spotted snake millipede, Blaniulus guttulatus (illustrated). These are up to 20mm long and creamy white with a row of red dots down the sides of the body. Millipedes are often more numerous in soils that have received generous quantities of organic manures.
Control
None of the pesticides currently available will give good control, so millipedes have to be tolerated. Avoid problems by growing potato cultivars that have some slug resistance and by lifting strawberry fruits off the ground by putting straw underneath them. Millipedes feed mainly on decaying plant material and so most millipede species are not harmful to growing plants.