6 DEPARTMENT OF AGRICULTURE BULS. 551-575. 



Department Bulletin No. 562. — The Control of Tobacco Wilt in the 



Flue-cured District — Continued. Page. 



Susceptibility of species and varieties of tobacco to the wilt 5 



Relation of the physical and chemical properties of the soil to the wilt 7 



Crop rotation as a basis for the control of the wilt 10 



Precautions to prevent the spread of the disease 17 



Summary 18 



Literature cited 20 



Department Bulletin No. 563. — The Determination of Bacteria in Ice 

 Cream: 



Difficulty of making accurate bacteriological analyses 1 



Method of sampling and plating the ice cream 2 



Variation in the bacterial content of commercial ice cream 3 



Variation when held in an ice-cream cabinet 8 



Variation when held in storage 9 



Variation in samples taken directly from freezer 10 



Comparison of incubation at 37° C. for two days and at 30° C for five days. 12 



Number of colonies of most desirable on Petri plates "... 13 



Variation between duplicate counts from same sample 14 



Interpreting differences in bacterial counts 15 



Summary and conclusions 16 



Department Bulletin No. 564. — Collection of Weevils and Infested 

 Squares as a Means of Control of the Cotton Boll Weevil in the 

 Mississippi Delta: 



General statement of experiments conducted 1 



Brief review of 1915 experiments 2 



Lines of investigation in 191 6 3 



Time interval between bag-and-hoop collections in relation to proportion 



of infested forms secured 3 



Plat tests of the value of the bag-and-hoop as a means of weevil control 



under field conditions 18 



Experiment on Hecla Plantation ; . . 18 



Eureka Plantation experiment No. 1 27 



Studies on the value of a mechanical collector of boll weevils 37 



Plat test. 38 



Comparative efficiency studies 41 



General considerations and summary 42 



Department Bulletin No. 565.- — How to Candle Eggs: 



Introduction 1 



Grading of eggs 2 



The egg candle 2 



The structure of the egg 3 



How to hold an egg when candling 5 



What to look for in candling an egg 6 



Classified description of eggs before the candle and out of the shell 12 



Department Bulletin No. 566. — The European Earwig and Its Control: 



Description and seasonal history 2 



Disagreeable habits of concealment 5 



Area infested 5 



Nethods of dispersion 7 



Natural enemies 7 



Control of the earwig 8 



Department Bulletin No. 567. — Increased Yield of Turpentine, and 

 Rosin from Double Chipping: 



More naval stores from same tree 1 



Plan of the experiments 2 



Yields 4 



Effect of double chipping on the trees 6 



Practicability of double chipping 7 



Returns from double clapping, in dollars and cents 8 



Summary 9 



