394 



How Living Things Affect One Another unit vii 



Fig. 345 The codling moth 

 (above) a?id larva in an ap- 

 ple (below). What is the 

 life history of the codling 

 moth? How can it he con- 

 trolled? (u. S. DEPARTMENT 



or agriculture) 



the bark on which it rests. You may well 

 have overlooked it, but you have all met 

 the larva in a "wormy" apple. Its life 

 history is shown briefly in the table on 

 this page. With an early start and favor- 

 able conditions this life history may be 

 repeated four times in a season. Spraying 

 should, therefore, be done in the spring 

 when the apples first begin to form. 

 Since the lead arsenate used is very poi- 

 sonous, the fruit should be thoroughly 

 washed before it is eaten. 



Contact poisons. Stomach poisons are 

 useless for control of insects that do not 

 have biting mouth parts in any stage of 

 their life history. Plant lice and the many 

 scale insects are of this kind. They punc- 

 ture the stem or leaf and suck the juices 

 of the plant. For such insects contact 

 poisons can be used. Some of these, such 

 as various nicotine compounds, enter or 

 clog up the insects' breathing pores 

 (spiracles). Insects have numerous 

 breathing pores which connect with tin\' 



Life History of the Codling Moth 



1. Moths emerge and lay eggs on leaves of apple trees. 



2. Eggs soon hatch into tiny caterpillars. 



3. Caterpillars crawl to the developing fruit and bore into it. 



4. Caterpillars eat and grow with the apple, often causing it to fall, 



5. Caterpillars eat their way to the surface and pupate. 



6. Pupae that form late in the season winter over in their cocoons. 



