Fig. 42.—Phthiraptera. Suborder Anoplura. Haematopinus asini, the blood-sucking horse louse. Actual length 0.1 inch.
| Legs fitted for running, as in [fig. 41], without large pincers at their ends; mouthparts situated near the middle of under side of the head and fitted for chewing. Occurring on birds and mammals. The chewing lice | Suborder Mallophaga |
| Legs fitted for clinging to hairs, each leg ending in a large pincer, as in [fig. 42]; mouthparts retracted within head, consisting of a set of thin, needle-like parts fitted for sucking blood. Normally occurring only on mammals. The sucking lice | Suborder Anoplura |
Suborder Mallophaga.
Individuals of many species of chewing lice move about with considerable rapidity. Many of them are very prettily banded and colored, as is the chicken head louse, Cuclotogaster heterographus (Nitzsch), [fig. 41]. Anyone who has worked with domestic fowls or animals has seen members of this order scurrying among the feathers or hair. These insects feed on what they can chew from the surface of the skin and in some cases are known to injure their hosts.
Suborder Anoplura.
The sucking lice are sluggish insects that usually cling to hairs. Human lice are often found clinging to clothing. Various species occur on native and domestic species of mammals in Illinois. [Fig. 42] shows the horse louse, Haematopinus asini (Linnaeus).
Thysanoptera
Thrips
Fig. 43.—Thysanoptera. Thrips tabaci, onion thrips. Actual length less than 0.1 inch.
Small, active insects, usually about 0.1 inch long, rarely a quarter-inch long, very slender, usually each with two pairs of narrow wings and with the under side of the head forming a sharp, conelike sucking structure. Each wing has a long fringe on the hind margin; each front wing may have one or two veins running the length of the wing. The young of these insects are somewhat similar to the adults but are softer bodied. [Fig. 43] shows an adult of Thrips tabaci Lindeman, the onion thrips. Thrips suck the juice from plants. Because of their minute size, they are seldom noticed, but they can be collected in large numbers from blossoms of almost any plant. A few species of thrips, such as the onion thrips and the privet thrips, attack agricultural or horticultural plants and inflict considerable damage. A few species occasionally bite human beings.