68 ELEMENTARY ENTOMOLOGY 



Thus we ascertain that it belongs to one of the several divisions, 

 called orders, into which all insects are divided, known as the 

 order Cole opt era. Some nineteen orders of insects are now recog- 

 nized by entomologists, but only six or seven are of any economic 

 importance. Most of the orders are distinguished by the structure 

 of the wings, and the names of the orders usually end in the syl- 

 lable ptem, trompteron, meaning "a wing." A brief survey of the 

 beetles shows that the order Coleoptera consists of numerous fami- 

 lies, which are grouped together according to the number of seg- 

 ments in the hind tarsi. An examination of the hind tarsus of a 

 ladybird beetle reveals that it is composed of but three segments, 

 which is characteristic of only one family, the Coccinellidae, the 

 family of the ladybird beetles. A brief account of this family indi- 

 cates that nearly all of its members are predacious upon plant- 

 lice or other small insects, and that the more common forms are 

 small yellow or red beetles with black spots, like the specimen in 

 hand. It is evident, therefore, that our ladybird beetle is feeding 

 upon the plant-lice and is in no way responsible for them, for a 

 similar study of the plant-lice would show that they belong to an 

 entirely different order (the Hemiptera), which has sucking mouth- 

 parts and an entirely different life history. We should also learn 

 from the account of the Coccinellidae that the little long-legged, 

 blackish, brilliantly marked larvae which accompany the ladybirds 

 are the young stage from which they develop, and that these larvae 

 also feed upon the plant-lice. Probably we should find several 

 different kinds of beetles, evidently all of the ladybird family, but 

 differing in size, shape, and coloration. Should we desire to speak 

 exactly of any one sort, we should be obliged to determine to what 

 genus of the family it belonged, and then to which of several 

 species in that genus. Usually the amateur will not be able to 

 identify an insect farther than to its family, but in the case of 

 common forms, especially those commonly injurious, the illustra- 

 tions or descriptions of the insect or its characteristic work as given 

 in textbooks, or the comparison of the specimen with those of 

 a named collection, if one is available, will make it possible to 

 definitely determine the species. 



Scientific names. The name of the gcnns and species together 

 is commonly called the scientific name, and is in Latin and usually 



