Small, rounded or flattened insects, rarely a quarter-inch long, usually about 0.13 inch. In many species, adults have two pairs of wings, which have only a few zigzagging veins. Winged forms, such as Psocus striatus Walker, [fig. 40], are found in crevices of bark and on dead leaves. Common species found in houses and on stored grain are usually wingless and louselike, similar in general appearance to [fig. 41]. Corrodentia eat fungus growth on bark, dead leaves, moldy grain, damp books, and similar materials. Some of the outdoor species become very abundant on drying corn leaves during autumn and may breed in immense numbers. They do little harm, feeding chiefly on fungus strands.
Phthiraptera
Chewing Lice, Sucking Lice
Wingless, blind, flattened insects with short antennae, short legs, inconspicuous mouthparts, and no tails on the posterior end of body. They are found exclusively on the bodies of birds and other warm-blooded animals. The young have the same general shape and habits as the adults and are found with them. Illinois species of lice belong to two distinct suborders, which may be differentiated through use of the following key:
Fig. 39.—Zoraptera. Zorotypus hubbardi, the only zorapteron recorded from Illinois. The specimen on the left is a winged adult female; the specimen on the right is a wingless adult female. Actual length of adults about 0.08 inch.
Fig. 40.—Corrodentia. Psocus striatus, a common bark louse found on many trees. Actual length 0.2 inch.
Fig. 41.—Phthiraptera. Suborder Mallophaga. Cuclotogaster heterographus, a chewing louse found on the heads of poultry. Actual length about 0.1 inch.
