214 THE PRINCIPLES OF FLORICULTURE 



life of a mature insect is usually short. Frequently they 

 eat but little, and exist only long enough to fulfill their 

 mission of laying eggs, or providing in other ways* for the 

 reproduction of the species. The few insects which pass 

 the winter in the adult stage usually bury themselves 

 underneath rubbish or in soil, and remain dormant. 

 Some outdoor insects pass the winter in the egg, and if 

 they can be discovered and destroyed in this stage, large 

 numbers of the young will perish. Many hibernate in 

 cocoons. 



238. Reproduction. Some insects give birth to living 

 young, while others reproduce by eggs. The larger part 

 come in the last group. 



239. Classification by feeding habits. There are 

 various ways of classifying insects, but for the purposes 

 of extermination, the classification most effective is that 

 which refers to the manner of taking food. They are 

 classed as biting or chewing insects, and as sucking 

 insects. 



A careful study of the mouth parts shows that chewing 

 insects have an upper and a lower lip. They also have 

 two pairs of jaws moving sidewise between these lips. 

 These insects have the power of tearing vegetable tissue 

 in pieces, and then swallowing it. In other insects, the 

 mouth parts have been so modified that they seem to 

 have no jaws at all. They have a long, beak-like organ, 

 with certain parts of which they puncture the epidermal 

 tissue of leaves and suck the juices of the plant. 



240. Methods of combating insect attacks. In view 

 of the fact that some insects chew the foliage, while others 

 only puncture the epidermis and suck the juices from the 

 tissue beneath, it is obvious that both classes cannot be 

 treated alike. In many instances, both .chewing and 



