14 ILLUSTRATIONS. 



Page. 



16. Status of the boll weevil in Texas in August, 1908; percentage of infestation 



of all forms 80 



17. Status of the boll weevil in Texas in August, 1909; percentage of infestation 



of all forms 81 



18. Status of the boll weevil in Texas in August, 1910; percentage of infestation 



of all forms 82 



19. Status of the boll weevil in Texas in August, 1911; percentage of infestation 



of all forms 83 



20. Curves of numerical strength of the boll weevil and its parasites 84 



21. The spread of the cotton-boll weevil from 1892 to 1911 88 



2'2. Diagram illustrating average length of hibernation period of the boll weevil 



as related to date of entering hibernation 1 06 



23. Diagram illustrating relations of effective temperature and precipitation to 



date of beginning emergence of the boll weevil 107 



24. Diagram illustrating average rate of emergence of the boll weevil from hiber- 



nation in Texas and Louisiana 109 



25. Diagram illustrating average longevity of boll weevils after emerging on a 



given date 115 



26. Diagram to illustrate the zones of temperature in their relations to the 



activities of the boll weevil 126 



27. Map showing dates of first killing frost in the area infested by the boll 



weevil, in the winter of 1909-10 129 



28. Map showing normal dates of first killing frost in the southern United States. 129 



29. Map showing minimum temperatures on October 29 and 30, 1910, the date 



of the first killing frost in Louisiana 130 



30. Map showing minimum temperatures in the winter of 1910-11 in Louisiana. 130 



31. Evarthrus sodalis an enemy of the boll weevil 138 



32. Chauliognathus marginatus an enemy of the boll weevil 1 38 



33. Hydnocera pubescens an enemy of the boll weevil 139 



34. Apparatus for fumigating cotton seed in the sack 163 



