KNTOMOLOGY IX OUTLINE CLASSIFICATION. 



9 



metamorphosis, the young resembling the matured members in every- 

 thing except size, and they have no antennae. Some of our greatest 

 orchard pests are found in this group, among them being the red spider 



FIG. 4. A scorpion (Buth *). Natural size. 



and various mites; the ticks, which so trouble our poultry and live 

 stock, also belong to this class, as do the phytopti, which infest our 

 pear trees and grapevines. The disease 

 known as the "itch" among men is also 

 caused by a member of this family, called 

 the itch mite. Some of the mites, during 

 the larval or undeveloped stage, have 

 six legs, acquiring their entire comple- 

 ment of eight only when fully developed, 

 and the phytopti have but four legs at 

 any period of their existence. These, 

 however, are exceptions to the rule 

 that members of this class have eight 

 legs. It will be observed from the above 

 that some of our most troublesome pests 

 are found in this class, but there are also 

 some that are beneficial. In fact, very 

 many of the spiders, which are generally 

 predaceous, perform a beneficial work in 

 keeping down injurious species. 



FIG. 5. Six-spotted mite (Tetranychus 

 macuiata). a, insect, much enlarged ; 

 b, tarsus ; c, rostrum and palpus, still 

 more enlarged ; rf, tip of palpus, still 

 more enlarged. 



CLASSIFICATION. 



In order to place properly an insect or 

 other natural object, a system of classi- 

 fication is necessary. As stated before, we have three great kingdoms- 

 All objects have distinguishing characteristics which place them nat- 

 urally in one or the other of these, and we know at a glance to which 



