16 



BULLETIN 67, UNITED STATES NATIONAL MUSEUM. 



up the sap of the plant. Although many species are very destructive, 

 there are several very useful insects, such as the cochineal and lac 

 insects; the former used for a dye, and the latter to make shellac. 



The suborder Anoplura (Pediculi) includes a few wingless para- 

 sites known as lice (fig. 28), which infest various mammals, including 



man. They are flat, 

 with short legs, the 

 tips of which end in 

 a large claw opposed 

 to a projection from 

 the preceding joint. 

 They should be col- 

 lected in alcohol ; or, 

 for study, mounted 

 upon slides, always 

 with the name of the 

 host. 



THYSANOPTERA. 



Fig. 2li. — A plant-louse, Rhopalosiphum violjE: a. Adult; 

 b, wings; c, larva; d, nymph. 



This small order is 

 based on tiny insects 

 known as "thrips" 

 (fig. 29). They are 

 slender, rather flat, 

 with pointed head, and short legs which end in two-jointed tarsi 

 without claws. The four wings are very slender, with few veins, and 

 fringed with long hairs. A few species, 

 however, have apterous females. Their 

 mouth-parts are peculiar, and their meta- 

 morphosis is incomplete. 

 They feed on vegetation and 

 are quite numerous, and 

 many fly during fine days in 

 the autumn and may be seen 

 on clothing, in houses, etc. 

 Others hibernate under loose 

 bark. All should be mounted 

 upon slides, care being taken to spread out the wings 



Fig. 27 .—A mealy bug, Dactylopius 



CITRI. 



Fig. 28.— The 

 head louse, 

 Pediculus 



CAPITIS. 



NEUROPTERA. 



These are biting insects with four large, many-veined 

 wings, and a complete or nearly complete metamorphosis. The 

 legs are of moderate size, and the tarsi have five joints. They are a 

 small order, and as many fly only at night they are not often seen 

 by the general collector of insects. There are three suborders. The 

 Megaloptera include large species like the horned Corydalis or hell- 



