Centipedes and Millipedes
Centipedes, many members of the class CHILOPODA
Millipedes, many members of the class DIPLOPODA, including the
Garden millipede, Oxidus gracilis Koch,
Paradoxosomatidae, POLYDESMIDA

DESCRIPTION

Adult -- Millipedes are gray-to-brown arthropods with worm-like, cylindrical bodies, usually 13 to 38 mm long, with a pair of short antennae. Adults have at least 30 pairs of legs with two attached to most body segments. Known as thousand-legged worms, millipedes walk slowly, their legs moving in a wave-like motion. They curl up tightly when disturbed.

Also elongate and worm-like, centipedes are known as hundred-legged worms and bear some resemblance to millipedes. They are different in that they have flattened bodies, a pair of long, slender antennae, a pair of claws just behind the head, and at least 15 pairs of legs, with only one pair on most body segments. They also move more rapidly than millipedes.

Egg -- White, creamy yellow, or brown, millipede eggs are smooth, spherical, and about 0.4 mm in diameter. They adhere in clusters due to the presence of a sticky secretion. Centipede eggs are similar.

Larva -- Smaller than adults, newly hatched millipede larvae have only three pairs of legs. Additional legs appear after each molt.

BIOLOGY

Distribution -- Millipedes and centipedes are cosmopolitan. Millipedes tend to live in dark, damp places, whereas centipedes usually inhabit places where they can forage for insects. Most of the pests encountered are millipedes, particularly the greenhouse millipede.

Hosts -- Moist, decaying organic matter is the primary food of millipedes. Centipedes, on the other hand, prey on insects and spiders.

Damage -- These arthropods are more of a nuisance than a threat. Millipedes occasionally feed on vegetation. Some species also exude a venom that blisters the skin and others emit an offensive odor. They do no significant damage to turf but are annoying when they leave their natural habitat and invade nearby buildings. Though some centipedes inflict a painful bite, the species most likely to enter houses does not.

Life History -- The life histories of these pests are not well-documented. The following information pertains primarily to millipedes, since these pests are more commonly encountered. In spring and again in fall, eggs are laid in clusters of 20 to 100 in the soil. Some females deposit as many as 300 eggs. Larvae emerge 9 days to 3 weeks later. Feeding on decaying vegetable matter, larvae grow slowly, developing through about 7 instars in 21 to 25 weeks. Adults are relatively long-lived. Millipedes overwinter in the soil or in other moist, secluded places.

CONTROL

The destruction of favorable feeding and breeding sites is the most reliable method of millipede control. Thatch should be removed from turf for millipede control and other reasons. Compost piles, mulches, and low growing vegetation should be located away from buildings to retard the entrance of these pests. Foundation walls should be repaired and cracks around doors, basement windows, and similar openings should be sealed. Millipedes and centipedes are less troublesome in properly ventilated basements and crawl spaces.

If a general clean-up does not eliminate problems with these pests, pesticides may be used. Millipedes are controlled by spraying a 5-m band around the foundations of club houses or shelters. Chemical control of centipedes occurs only indoors. For recommended insecticide and rates, consult state agricultural extension service recommendations.