UNITED STATES DEPARTMENT OF AGRICULTURE 



% BULLETIN No. 926 $ 



^MMn *^i^lZ? Contribution from the Bureau of Entomology ^2 



2&?*'$£su L- O. HOWARD, Chief JZ^'^^U 



Washington, D. C. 



PROFESSIONAL PAPER 



April 19, 1921 



STUDIES IN THE BIOLOGY OF THE MEXICAN COTTON 

 BOLL WEEVIL ON SHORT-STAPLE UPLAND, LONG- 

 STAPLE UPLAND, AND SEA-ISLAND COTTONS. 



By George D. Smith, Entomological Assistant. Southern Field-Crop Insect 



Investigations. 



CONTENTS. 



Page. 



Introduction 1 



Historical review 2 



Scope of the present life-history 



studies 3 



Methods used in the study of the 

 boll weevil under outdoor insectary 

 conditions 3 



Methods used in the study of the 

 biology of the boll weevil under 

 field conditions 4 



Food plants of the boll weevil 5 



The boll weevil on sea-island cotton- 6 



Longevity of adult boll weevils on 



upland and sea-island cottons 7 



The size of the cotton square at- 

 tacked by boll weevils 10 



Locations selected for oviposition 

 on sea-island and upland cotton 

 squares 11 



Period from emergence to ovi- 

 position 11 



Oviposition period of the boll weevil 



under insectary conditions 11 



Summary of the fecundity of the 

 boll weevil on sea-island and up- 

 land cottons under insectary con- 

 ditions 13 



The average developmental period of 

 the cotton boll weevil under out- 

 door insectary conditions 14 



The developmental period of the boll 



weevil under field conditions 15 



Egg-laying activity of hibernated 

 female weevils under field con- 

 ditions 19 



Page. 



Length of time upland cotton 

 squares hang on the plants after 

 egg puncture . 20 



Fecundity records of hibernated fe- 

 male boll weevils on upland cotton 

 under field conditions 21 



Summary of the developmental 

 period of the first generation boll 

 weevils in upland cotton squares 

 under field conditions 22 



Developmental period of first genera- 

 tion boll weevils on short-staple 

 upland, sea-island, and long-staple 

 upland cottons under field condi- 

 tions 23 



Comparison of the developmental 

 period of the immature stages of 

 the boll weevil under field and in- 

 sectary conditions 25 



Developmental period of the boll 



weevil in green cotton bolls 27 



Fecundity of the boll weevil in up- 

 land and sea-island cotton bolls 28 



The relation of temperature to the 



biology of the boll weevil 30 



The developmental period of the boll 



weevil on different types of soil 32 



The effect of the determinate growth 

 of the cotton plant on the biology 

 of the boll weevil 32 



Hibernation of the boll weevil in 



Florida 33 



General summary 43 



INTRODUCTION. 



The studies in the biology of the Mexican cotton boll weevil (An- 

 thonomus grandis Boh.) upon which this paper is based were con- 



a The cotton varieties used in these studies were a short-staple upland cotton known 

 as King, a long-staple variety known as Webber No. 49, and a sea-island cotton known 

 as Hope Straight. 



16073°— 21 1 



