Diplopoda: millipedes

Characteristics
Millipedes are a diverse group of animals and are not well studied in Australia and of the 15 orders of millipedes in the world only 9 have been recorded in Australia. Millipede means 'thousand feet' but they do not really have this many, although most have over 30 pairs of legs and some are known to have about 350 pairs. Millipedes can be distinguished from other invertebrates by the following characters:

• 2 pairs of legs per body segment, although some juveniles may posses only 1 pair per segment

• Simple eyes if present, although many have no eyes

• 1 pair of antennae

• Chewing mouthparts

Although it looks like millipedes have 2 pair of legs on each segment, closer examination shows that each body segment is actually 2 segments fused together. Millipedes are timid invertebrates and unlike centipedes, do not have poisonous claws so to protect themselves and to discourage predators they roll into a tight spiral and often discharge a foul smelling, distasteful substance.

The introduced species Ommatoiulus moreletii (Black Portuguese millipede), often reaches plague proportions in southern Australia invading houses and destroying crops. Numbers can be so great in places that the ground appears a wriggling mass of black millipedes.

Life Cycle
Most male millipedes have specially designed mating legs on their seventh body segment, which they use to transfer sperm to the female genital opening. The female then lays her eggs in the soil, under logs or among leaf litter depending on the species. The newly hatched young have 3 to 4 pairs of legs depending on the species. Body segments and legs are added with successive moults as they grow until the adult size is attained.

Feeding
Millipedes are herbivores and scavengers, feeding primarily on decaying plant material and animal matter.

Habitat
Most millipedes are found in cool, moist environments and many species are common under rocks and logs, in leaf litter and soil and under the bark of trees.

The black Portuguese millipede Ommatoiulus moreleti, is an introduced species which has rapidly gained a reputation for being a nuisance pest in most areas where it occurs.

This species often reaches plague numbers especially in southern Australia. In these instances it often invades houses and other dwellings where it contaminates food and infests carpet and bedding. It may also destroy fruit and vegetable crops.

Like other species of Julid millipedes the black Portuguese millipede discharges a yellowish liquid when disturbed to discourage predators. Although not dangerous to humans this fluid can stain skin and material.