Nature Bulletin No. 244-A   November 12, 1966
Forest Preserve District of Cook County
Seymour Simon, President
Roland F. Eisenbeis, Supt. of Conservation

****:CENTIPEDES AND MILLIPEDES

Our dislike for things that crawl in dark damp places seems to have 
come down to us from the dim past; perhaps from the days when our 
ancestors shared caves with them. Many of us shudder when we come 
across one of these creatures in damp basements, in gardens, under 
rocks and rotting logs, or among leaves and trash. Among these 
dwellers in darkness, besides worms and slugs with no legs, insects with 
six legs, spiders and daddy-long-legs with eight, and pill bugs with 
fourteen, there are two sorts with a multitude of legs. These are the 
Centipedes and the Millipedes. They are not worms but are long slim 
animals with many legs and segmented bodies enclosed in jointed 
shells.

The centipedes, of which about 1200 kinds are known in the world, 
have one pair of legs attached to each body segment -- from 12 to 60 
pairs according to the kind. Most of them feed on insects and other 
small prey which they kill or paralyze with poison injected through the 
claws on the front pair of legs. Some large tropical species, which 
become a foot long or more, can inflict painful bites but our native 
centipedes are almost harmless.

While others are outdoor creatures, the House Centipede is often seen 
rushing over walls and floors of houses when a light is turned on, or 
trapped in a bathtub or sink -- to the dismay of a housewife. Its flat 
ribbon-like body is only an inch or so long, with a pair of very long 
slender "feelers" on the head and 15 pair of long legs arranged along 
the sides. the last pair being more than twice the length of the body. It is 
grayish yellow in color, marked with three dark lengthwise stripes, and 
the legs are banded with white. It runs rapidly but often halts, remaining 
motionless, and then races for concealment in some crack or crevice. It 
is the only centipede that thrives and breeds in houses, often wandering 
into the upper floors. There have been a few instances of bites by them 
but the symptoms are not severe. Actually, they are beneficial because 
they feed upon cockroaches, flies, moths, spiders and other small 
creatures about the house. The tiny whitish Garden Centipede, found in 
cracks in soil and about the roots of plants, is only a little over 1/4 inch 
long when full-grown and has 12 pairs of short legs.

The millipedes, or Thousand-leggers, are among our most primitive 
land animals. Their fossils, some over a foot long, are found among the 
swamp plants that went into the formation of coal. They differ from 
centipedes in having rounded bodies and two pairs of short legs on each 
joint or segment, except the first three which have only one pair each. 
Some kinds may have over 200 pairs, and there are about 1300 kinds 
known over the world, ranging in length from a twelfth of an inch to 8 
inches. Although they sometimes invade houses, they are entirely 
harmless to man and feed on decaying vegetable matter, on decaying 
wood, and often on the tender roots of plants or even green leaves that 
touch the ground. Sometimes they tunnel into the fleshy parts of garden 
crops and do damage.

Millipedes crawl with a slow graceful gliding movement unlike the 
rapid wiggling of the centipedes. Waves of movement pass down the 
rows of legs like a column of soldiers a little out of step. V~/hen 
touched, they curl up and "play dead". In our Chicago woodlands, 
under fallen leaves and fallen logs, we often find a large mahogany-
brown one, called Spirobolus, which is about as big as a king-size 
cigarette and has over a hundred pairs of legs. To protect itself from 
enemies, it gives off an offensive odor from special stink glands -- 
strong enough to kill small insects.

There are also two-legged stinkers.