SPECIAL PROBLEMS OF INSECT CONTROL 151 



Water will not do this, because the openings are protected 

 against its. entrance by oily secretions. Compare the effect 

 cf dipping an insect into water and into kerosene. 



Next, beginning at the head, study all organs and mov- 

 able parts (appendages) : the eyes, feelers (antenna^, replacing 



Head Prothorax Mesothorax Metathorax Abdomen 

 Compound Eye \ j 



Simpte Eye/ 



/ / . Hind Wing 



X">x" 



Ear 



Antennfi', 

 Lal)rum .. 



Spiracles 

 Trochanter 



Legs- 

 Mandible 

 Maxilla 



''Femur 

 ''--.Tibia 

 '''^.Tarsus 



Labium 

 Mouth-Parts 



vipositor 



EIG. 77. External anatomy of the grasshopper 



( ars and nose as sense organs, at least partly), mouth parts 

 ( very complicated, consisting typically of an upper and lower 

 lip (labrum and labium) and two pairs of jaws (mandibles 

 find maxillae), which move sidewise instead of up and down). 

 Watch a caterpillar or grasshopper eat a leaf and see if you 

 can discover why the jaws move sidewise. A study of mouth 

 I >arts is again important with reference to methods of destroy- 

 iag insects. Those that bite and chew can be killed by spraying 



