CONTENTS. 



> Page. 



Introduction 9 



Economic importance , 9 



Life history 10 



Hibernation 10 



Aphides on hop roots 10 



Emergence from hibernation 12 



Method of reproduction 12 



Number of generations on alternate host 13 



Migrating forms 13 



Migratory activities 13 



Deposition of young 14 



Rate of growth 15 



Number of young deposited by viviparous females 16 



The fall migrants 17 



The winter egg 17 



The life cycle 18 



Theory regarding summer migrants 18 



Habits 19 



Habitation 19 



Protection 19 



Relation of ants to the hop aphis 19 



First appearance of the hop aphis in the season 20 



Favorable and unfavorable conditions for the aphis 20 



Effect of heat 20 



Food plants 21 



Nature of damage 21 



General effect of aphides upon hops 21 



Honeydew and its effect on the hops 22 



Blackening of hops 22 



Natural enemies 22 



Control of the hop aphis 23 



Axioms of successful control 23 



Insecticides used 23 



Time to begin spraying 23 



Number of applications 24 



Necessity for early spraying 24 



Necessity for thorough work 24 



Procrastination 24 



Spraying experiments : 24 



Mixing nicotine solutions and whale-oil soap 27 



Preparation of the flour paste 27 



Advantages of flour paste over whale-oil soap as a spreader for contact insec- 

 ticides 28 



5 



