INSECTS 187 



the poisoned plant tissue. If the insect gets its food by suck- 

 ing, spraying with a poison will not be successful. The 

 sucking tube of the insect by means of which it gets its food 

 will penetrate the surface of the plant, and little or no poison 

 will be taken into the body. Consequently other measures 

 must be taken to destroy such insects. If a spray mixture 

 is used, it must be one that will cor- 

 rode or otherwise injure the bodies 

 of the insects, such as the lime-sulfur 

 mixture so commonly used to destroy 

 scale insects; or one that will cover 

 their bodies in such a way as to affect 

 the breathing organs, such as the 

 kerosene emulsion often used to de- g an j ose g ca i e Several 



Stroy plant lice. adul t insects considerably 



c- -, . T i magnified to show details 



Sucking insects, such as scale in- of appearance> 

 sects, may also be destroyed by 



another method. The infected plant may be covered with 

 a tent, and a poisonous gas, such as hydrocyanic acid gas, 

 generated beneath it. The gas enters the breathing pores 

 of the insects and they soon die. 



What a farmer should know about insects. The four 

 great facts many kinds of insects, rapid reproduction, 

 rapid growth, and a successful means of meeting adverse 

 conditions should be recognized by the farmer in order 

 that he may be on his guard and take measures for the control 

 of insects. 



The farmer should be familiar with the life histories of 

 the most common injurious insects. At least he should know 

 that caterpillars are the larvae of moths and butterflies, 

 grubs the larvae of beetles, maggots the larvae of flies, that 

 young grasshoppers resemble the adult forms except in size 



