UNITED STATES DEPARTMENT OF AGRICULTURE 



1 BULLETIN No. 932 



^klV^viS^il^C Contribution from the Bureau of Enlnninlncv «I 



iv^"^5L 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



S\J^*^pWu 



Washington, D. C. 



PROFESSIONAL PAPER 



September 20, 1921 



LIFE HISTORY OF THE CODLING MOTH IN THE 

 GRAND VALLEY OF COLORADO. 



By E. H. Siegler, Entomologist, and H. K. Plank, Scientific Assistant, Fruit 

 Insect Investigations, in cooperation with The Colorado Agricultural 

 Experiment Station. 



CONTENTS. 



Introduction 



The Grand Valley of Colorado 



Explanation of terms 



Methods and rearing apparatus em 



ployed in the life-history studies 



The insectary 



Seasonal-history studies of 1915 



Wintering larvae 



Pupae of the spring brood 



Moths of the spring brood 



The first generation 



The second generation 



The third generation 



Codling-moth band studies of 1915— 



Seasonal-history studies of 1916 



Pupae of the spring brood 



Moths of the spring Drood 



The first generation 



The second generation 



The third generation 



Codling-moth band studies of 1916— 

 Natural enemies of the codling moth 



Miscellaneous studies 



Effect of cool temperatures on 

 emergence of moths of the spring 

 brood 



Page. 

 1 



9 

 10 

 10 

 12 

 17 

 31 

 40 

 40 

 45 

 46 

 48 

 52 

 66 

 75 

 78 

 82 

 83 



83 



Page. 

 Miscellaneous studies — Continued. 



Time of day moths emerge 84 



Codling moth flight trials 87 



Time of copulation 89 



Time of day moths oviposit 91 



Oviposition by individual moths. 99 



Deposition of infertile eggs 106 



Time required for codling moth 



larva to leave the egg 107 



Larvae that fail to extricate them- 

 selves from the chorion 107 



Habits of newly hatched larvae_. 108 



The codling moth "sting" 3 08 



Codling moth larvae feeding on 



pear twigs 108 



Experiments with black and white 



bands 109 



Percentage of transforming and 



wintering larva? 111 



Laspeyresia pomonella (L.) var. 



simpsonii (Busck) 111 



Review of seasonal-history studies of 



the codling moth in 1915 and 1916. 112 

 Summary 115 



INTRODUCTION. 



The codling moth, Laspeyresia pomonella (L.) (PI. I, A) is 

 generally recognized as the most serious insect pest attacking the 

 fruit of the apple and pear and is particularly abundant and destruc- 

 tive in the Grand Valley of Colorado. As a result of the extensive 

 injury to the fruit industry of this valley for which this insect is re- 

 sponsible, it was deemed desirable to make a thorough study of its 

 life history as a basis for control experiments. 



19552°— 21 1 



