U. S. D. A., B. E. Bui. IIS, Part I. D. F. 1. 1., August <J, 1912. 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



LIFE-HISTORY STUDIES ON THE CODLING MOTH IN 



MICHIGAN. 



By A. G. Hammar, 

 Entomological Assistant. Deciduous Fruit Insect Investigations. 



INTRODUCTION. 



During the last four years the Bureau of Entomology has main- 

 tained a temporary held station at Douglas, Mich., for the purpose of 

 investigating certain deciduous fruit insects. As a part of this work 

 the present paper brings together the results for 1909, 1910, and 1911 

 of a detailed study of the life history of the codling moth (Carpocapsa 

 pomonella L.). This investigation has been conducted on the general 

 plan of the earlier work on this insect by the bureau as reported in 

 1909 by E. L. Jenne in the Ozarks and in 1910 by the writer in 

 Pennsylvania. 



During the season of 1909 the rearing work was carried out by 

 Messrs. R. W. Braucher and W. Postiff; in 1910 and 1911 by the 

 writer, assisted by Mr. E. R. van Leeuwen. In 1911 Mr. E. H. 

 Siegler was also detailed to assist in the rearing work and has in 

 addition aided the writer in the preparation of the manuscript tables. 

 Mr. E. W. Scott, conducting various spraying experiments at the 

 field station, has contributed valuable field observations. The writer 

 wishes to express special thanks to many of the fruit growers of the 

 Michigan fruit belt, who have facilitated this work both with valuable 

 information and numerous courtesies, and to Prof. A. L. Quaintance, 

 in charge of deciduous fruit insect investigations, whose practical 

 suggestions throughout the course of this work have been of great aid. 



A duplication of many rearing experiments for 1910 and 1911 became 

 necessary because of the unprecedented seasonal condition during 

 the spring of 1910, when the fruit crop was to a very great extent 

 destroyed by the sudden alternations from warm to cold weather. 

 The season of 1911 was very exceptional for its extreme heal, which 

 is strikingly reflected in the rate of development of the insect dining 

 that year. The rearing work during the more normal season of 1909 

 was greatly limited owing to the stress of other work, and the rearing 

 experiments for that season cover merely the more essential features 

 of the life history of the codling moth. The results thus gathered 



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