HOW TO KNOW THE INSEGS 



juncta (Germ.) and Leptlnotarsa pensularls Horn belong to this 

 same genus. The "decimllneata" is the species najne. It refers 

 to the ten stripes In evidence on the back of the adult beetle. 

 "(Say)" tells us that Thomas Say, a noted American entoFiOloglst 

 described this beetle In 1823 before it had become a pest of 

 potatoes. It was first called Doryphora decimllneata Say but 

 later referred to Its proper genus. 



ViThen nature v/as making the Insects she was In a most prolific 

 mood. The total of known species Is so great that we must have 

 som.e carefully organized system of "filing" not to become wholly 

 lost in the maze of numbers. We have Just seen how very closely 

 related species have a common generic name. In the same way 

 closely related genera (relationship is judged by similarity of 

 Important structures) are grouped into families. Families In 

 turn fall into great groups known as orders; orders unite in a 

 class and classes form a phylum. 



The whole group of the world's known animals may be divided 

 into eleven phyla. One of these includes all animals having seg- 

 mented bodies and jointed appendages. They are known as Arthro- 

 pods and include such animals as the crawfish, lobsters, crabs, 

 centipedes, millipedes, spiders, ticks, mites and Insects. The 

 Insects differ from these others in having just six legs. 



They constitute the most 

 abundant form of animal life. 

 In fact there are more known 

 species of Insects than there 

 are of all other animals and 

 all the plants put together. 

 This class distinguished by 

 six legs Is knov/n as the In- 

 sec ta or Hexapoda. 



Such matters as metamorph- 

 osis, mouth parts, number and 

 kinds of wings, and types of 

 legs divide the class Insecta 

 Into twenty-five orders. The 

 beetles, which belong to the 

 order Coleoptera, are, per- 

 haps, the best known of the 

 Insects for they have long 

 been favorites with Insect 

 collectors. They are found 

 everywhere; many of them are 

 marvelously beautiful In 

 their markings and coloration; they are easily mounted and kept. 

 Over 250,000 species of beetles have been named and described, 

 making this the largest known order. In our country more than 

 20,000 species have been recorded and about 3,000 species are 

 known to occur in Iowa. 



Other large orders are the Hymenoptera (bees, wasps, and 

 ants) and the Dlptera (two-winged flies) about which entomolo- 

 gists know much less than they do of beetles. It is thought by 

 some that both of these orders will prove to be larger than the 

 Coleoptera. The Lepldoptera (moths and butterflies) have been 

 much collected because of their beauty and general Interest. The 

 Hemiptera (true bugs), another fairly large order, is perhaps 



Figure 1. Considerably more than half of 



all the living things in the world are 



insects. 



