58 HOW ARE ANIMALS AND PLANTS DEPENDENT? 



Laboratory Exercise. How to identify an insect. If possible, use 

 a living bee from an observation hive, although some observation may 

 be made in the field and reported to the class. 



Examine its body carefully. Notice that it has three regions : a front 

 part or head; a middle part, the thorax, divided into three portions or 

 segments; and a hind portion, segmented 1 and hairy, the abdomen. 



How many pahs of legs does it have ? The legs, j ointed and provided 

 with tiny hooks at the end, are attached to the thorax. Two pairs 

 of delicate wings are attached to the upper or dorsal side of the thorax. 

 To which segments of the thorax are they attached? The entire body 

 has a tough covering or exoskeleton composed of chitin (kitin), a sub- 

 stance 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 interior of the exoskeleton, for there is no internal skeleton. 



Is there any movement of the abdomen of a living bee? The animal 

 breathes through tiny openings called spiracles (spir'a-k'l), which are 

 found on each segment of the abdomen and lead into branching air 

 tubes. Bees have compound eyes composed of numerous units called 

 ommitidia. Simple eyes or ocelli are usually also present. Bees are 

 provided with a pair of jointed feelers called antennae. Wings are 

 not found on all insects, nor is a vesture ; but the other structures just 

 given are characteristics of the great group of animals we call insects. 



simple eye 



compouncC e^e. 



antenna 



heacC 



rtxcJe 



jsting 



The honeybee. How many of the parts labeled here can you find on your specimen ? 



Common forms of insects. Inasmuch as there are more than 

 450,000 different kinds of insects, it is evident that it would be a 

 hopeless task for us even to attempt to recognize all of them. 



1 Segmented (seg'ment-ed) : separated into sections or parts. 



2 Vesture (ves'tux) : a covering. 



