572 



BIOLOGY AND HUMAN LIFE 



2. Insects parasitic on plants 



Locust 



Potato beetle 

 Cotton-boll weevil 

 Gypsy moth 

 Brown-tailed moth 

 Codling moth 



3. Insects injurious to animals 



(Disease-carrying insec 



Botflies 



Ox warble 



4. Combating insects 



Use of predatory and parasitic insects 



Ladybird ; calosoma beetle ; tachina fly ; ichneumon flies 

 Use of parasitic fungi 

 Spraying 



To control biting insects (beetles, larvae of moths, etc.) 



Paris green ; acetate of lead ; arsenate of lead 

 To control sucking insects (bugs, aphids, flies) 

 Soap solutions Nicotin solution 



Lime-sulfur solution Kerosene emulsion 



Fumigation of orchards etc. 

 Rotation of crops 

 Burning of stubble etc. 



Encouraging natural enemies (birds ; frogs and toads ; snakes ; 

 tiger beetles, ground beetles) 



5. The balance of nature 



How change in the numbers of one species may affect other 

 species 



Increase : decrease 

 Effect of migration or transplantation 



Favorable ; unfavorable 

 Practical importance 



QUESTIONS 



1. What are the most common injurious insects in your region ? What 

 harm do they do ? 



2. W^hat amount of damage is done by insects in your region to any 

 particular crop or species of plant ? to any animals ? 



3. What amount of damage is done by a particular species of insect ? 



