CONTENTS. 7 



Department Bulletin No. 419. — The Grape Leaf-Folder — Contd. page_ 



Life history and liabits 7 



Natural enemies 8 



Methods of control 12 



Literature cited .' 13 



Department Bulletin No. 420. — Cooling Hot-Bottled Pasteurized 

 Milk by Forced Air: 



Introduction 1 



Description of experimental apparatus 2 



Description of instruments and methods of recording data 3 



Relative rate of cooling of milk and water 5 



Tlelative rate of cooling of milk with still air and forced air 5 



Results of cooling by means of forced air .....,,..,,,.,-,---, r .,.-,,,,. . 9 

 Temperature variations in quart bottles of milk and water under varying 



conditions 19 



Cost of cooling by means of cold outside air 23 



Effect of slow cooling on the bacterial flora of milk after pasteurization 26 



Effect of the process on the cream line and flavor of milk 30 



Experiments in heating bottled milk by forced air 32 



General summary 35 



Conclusions 37 



Department Bulletin No. 421. — The Sugar-Beet Thrips: 



Introduction 1 



General description 1 



History 2 



Distribution 2 



Food plants 2 



Extent and nature of injury 3 



Habits of nymjahs of first and second stages 3 



Habits of nymphs of third and fourth stages 4 



Habits of the adult 4 



Descriptive 5 



Life cycle 9 



Control 10 



Bibliography 11 



Department Bulletin No. 422. — The Eggplant Tortoise Beetle: 



Introduction 1 



Distribution 1 



Host plants 1 



Description 2 



Development 3 



Enemy 6 



Experiment with arsenicals 6 



.Summary 7 



Bibliography 8 



Department Bulletin No. 423. — Labor Requirements of Dairy Farms as 

 Influenced by Milking Machines: 



FactH brought out 2 



Source.s of data 2 



Areas .studied 5 



Labor requirornentH of dairy farm ') 



Size of herd and labor requirements 7 



Tlie milking maf.hine H) 



