Nature Bulletin No. 491   April 27, 1957
Forest Preserve District of Cook County
Daniel Ryan, President
Roberts Mann, Conservation Editor
Ramon Swishe, Senior Naturalist

****:MITES

Spiders, scorpions, daddy-long-legs, ticks and mites are creatures 
known as arachnids. When adult they have eight legs. Insects have six. 
Mites and ticks differ from spiders by having the head, thorax and 
abdomen all fused into one oval-shaped baglike body. Throughout the 
world, many thousand species of mites have been identified and every 
year new kinds are found.

Mites vary greatly in appearance and habits. They range in size from 
those 90 small that they cannot be seen without the aid of a microscope, 
up to some which are about one-half inch long. Some of the tiniest are 
wormlike and suck the juices of plants, causing blemishes and galls. 
Other pigmies live in the breathing passages of bees. Mites vary in 
color from white and pale yellow, gray or green to brilliant red or 
orange.

Mites have three stages in their life history: egg, nymph and adult. A 
few species bear their young alive but, generally, the female lays from 
two dozen to a hundred or more eggs. From the egg is hatched a nymph 
much smaller than the adult but similar in appearance except that, in 
most species, it has only six legs. The nymph feeds, grows and, from 
time to time, sheds (molts) its tough outer covering when that becomes 
too small. From the last molt emerge an eight-legged fully equipped 
adult.

Some mites live in the ground; others in surface litter where they feed 
on tiny insects or on decaying matter. Some, including several gaily 
colored kinds, live and swim in fresh water; others in salt water. Some 
are parasites that live on the outside of animals' bodies but some burrow 
into the body. Species such as the soil mites, and those that prey on 
weevils or other injurious insects, are beneficial. Many, however, are 
serious pests in gardens, truck farms, orchards, greenhouses, homes, 
places where foods are stored, on poultry and on wildlife. There are few 
kinds that are dangerous because they transmit certain diseases or cause 
skin injuries.

In spring, little red mites are often found on freshly turned soil in 
gardens and fields. These may be chiggers or they may be pests which 
feed on beans, strawberries, clover or other plants, causing the leaves to 
curl, turn yellow and die. Another mite, called "the red spider", 
annually does much damage in orchards and to other trees and shrubs. 
There are numerous species named for the kinds of forest and shade 
trees, grains, and foodstuffs they attack. It has been difficult to control 
the "plant mites" because of their well-protected breathing apparatus, 
their natural immunity to some poisons, and their tendency to build up 
resistance to others.

Poultry mites usually hide in the henhouse during daytime and attack 
the fowl while roosting. One kind sucks their blood; another irritates the 
skin and causes the bird to lose its feathers; a third causes the feet and 
legs to become inflamed, swollen and scaly.

A number of mites are parasites on man. The tiny hair follicle mite, 
found on the nose and ear, is harmless but the itch mite, which burrows 
under the skin, causes intense itching and scabies or mange. Some 
species are known to transmit diseases such as Texas fever, yellow 
fever, and a typhus-like disease. The worst pest is the chigger mite or 
"redbug" which, in some countries, carries scrub typhus. The adults are 
harmless but the nymphs attach themselves to a person's skin, suck 
blood, and cause great discomfort.