HOW TO TELL AN INSECT 



25 



Antenna 



On any bright warm day in the fall we shall find insects swarming 

 in a vacant lot or in a city park. Grasshoppers, butterflies alight- 

 ing now and then on the flowers, brightly marked hornets, bees 

 busily working over purple asters or goldenrod, and many other 

 forms more or less hidden away on the leaves or stems of plants, 

 may be seen. If we select for observation some partly decayed 

 tree, we find it also inhabited. Beetles will be found boring 

 through its bark and wood, while caterpillars (the young stages of 

 butterflies and moths) are feeding on its leaves or building homes 

 in its branches. Everywhere above, on, and under ground may 

 be noticed small forms of life, many of them insects. Let us first 

 see how we should go to 

 work to identify some of 

 the common forms we are 

 likely to find on plants. 

 Then a little later we shall 

 find out what they are 

 doing on these plants.^ 



How to tell an Insect. 

 — A bee is a good ex- 

 ample of the group of 

 animals we call insects. 

 If we examine its body 

 carefully, we notice that 

 it has three regions : a 

 front part or head, a mid- 

 dle part called the tho'rax, which is divided into three parts or seg- 

 ments, and a hind portion, segmented and hairy, the dbdo'men. The 

 three pairs of legs, which are jointed and provided with tiny hooks 

 at the end, are attached to the thorax. How many joints can you 

 find in each leg? Two pairs of delicate wings are attached to the 

 upper or dorsal side of the thorax. The entire body has a tough 

 covering or exoskeVeton composed of chitin (ki'tin), a substance 

 chemically much like a cow's horn. This exoskeleton in the bee is 

 partly covered with tiny hairs which form a vesture over the body. 

 The muscles, which provide for movement, are fastened to the exo- 

 skeleton, for there is no internal skeleton. If we watch the abdomen 



^ If the teacher desires, Chapter XXI may be used at this point. 



A bee viewed from the side. Notice the head, 

 thorax, and abdomen. What other parts do you 

 find? What structures, if any, are joined to each 

 of these three body di\'isions? 



