DETERMINING NATURE OF ORGANISMS 271 



(a) Consider the Feeding Habits of Insect Pests. Control 

 of insect pests may best be approached from a study of their 

 methods of feeding. Chewing insects possess hard mouth 

 parts with which they bite off portions of the leaves, plant, 

 fruit, etc., actually taking some of these materials into their 

 bodies. The tent caterpillar and codling moth are illustra- 

 tions, both being destructive in the larval stage. The former 



Fig. 100. Some insects with biting mouth parts, (a) Grasshopper. 

 (b and e) Beetles, (c and d) Sawfly larvae. (/) Caterpillar. 



feeds chiefly on the leaves, the latter chiefly on the fruit. See 

 Fig. 100. 



Sucking insects possess mouth parts in the form of a beak 

 or slender tube which they insert beneath the exterior surface 

 of the object on which they are feeding, drawing or sucking 

 the juices from within the tissues. The San Jose scale and 

 aphids, or plant lice, are examples. The mosquito illustrates 

 the same type of feeding on human beings. See Fig. 101. 



