214 



THE INSECTS— ARTHROPODS 



of the body where needed. These distribute the oxygen much more 

 readily than can be done with lung or gill respiration and give insects the 

 tireless energy which enables them to accomplish so much in spite of 

 their small size. However, this method of respiration makes them very 



Head Thorax 



Abdomen 



Antennae 



Auditory organ 

 Compound ey( 



Spiracles 



Femur 

 Tibia 

 Tarsus 



Foundations of Biology, Woodruff, The Macmillan Company 



Fig. 15.4. Side view of a grasshopper. The typical characteristics of an insect are 



shown in this drawing. 



susceptible to foreign substances in the air for they are quickly dis- 

 tributed over the body. We take advantage of this by spreading insecti- 

 cides in the form of sprays or dusts. A beekeeper can make a hive of 

 bees quite docile by blowing a few puffs of smoke in at the top of the 

 hive. Chickens can often be seen "delousing" themselves by sitting in 

 a nest of fine dust and working it through their feathers so that the 

 lice are killed by a clogging of their spiracles by the fine dust particles. 



Courtesy General Biological Supply House 



Fig. 15.5. Portion of the eye of the horsefly. The typical arrangement of facets that 

 compose a compound eye is shown in this photograph. 



