PROBLEiM 3. Houo We Try to Solve Our Insect Froblems 



395 



TIME TO SPRAY 



POWER SPRAYER 



FRUIT FROM UNSPRAYED TREE 



FRUIT FROM SPRAYED TREE 



Fig. 346 What do you learn about codling moth control fro/n these four pictures? 

 Note especially the heaps of sound and voorviy apples from unsprayed and sprayed 

 trees, (hylson — u. s. bureau of entomology) 



air tubes (tracheae) that branch to all 

 parts of the body. The insect inhales by 

 enlarging its abdomen, thus allowing air 

 to enter the tubes. When the abdomen is 

 made smaller the tubes are compressed 

 and air goes out. You can see what hap- 

 pens to the insect when the breathing 

 pores are clogged. It dies from lack of 

 oxygen. 



Other contact poisons kill in different 

 ways. The effective insect exterminator, 

 DDT, developed during World War II, 

 is applied as a dust or spray. The poison 

 enters the insect's body through the feet 

 and travels to vital parts. Scale insects on 

 fruit trees are sometimes killed by apply- 

 ing poisonous chemical fumes to the 

 vvhole tree which is first covered with a 

 sort of tent. 



It is sometimes more convenient to 

 keep the insect away than to try to kill 

 it. Chemicals that can be used in this way 

 are called repellents. You use a repellent 

 when you pack your clothes with cam- 

 phor or naphthalene to protect them 

 against the clothes moth. It is the larvae 

 of the clothes moths that eat holes in 

 furs or woolen clothes. The tiny moth 

 you try to slap to death between your 

 hands is harmless, for it has already laid 

 its eggs before it leaves its dark hiding 

 place. Repellents are also used to protect 

 some plants. You will find Exercises 4 

 and 5 helpful. 



Using allies in the fight against insects. 

 The Bureau of Entomology in Washing- 

 ton has long encouraged us to protect 

 such birds as the bluebird, catbird, and 



