ON THE LIFE HISTORY OF THE 

 CODLING-MOTH* 



by Stephen a. foebes and peessley a. glenn 



The extraordinarily hot and dry summer of 1914 so stimulated 

 the development of the codling-moth in Illinois and advanced the 

 progress of its life history that the spraying programs of apple 

 growers, based, as they were, on the course of events in an ordinary 

 year, were out of gear with those of that unusual season, and 

 failed to control injuries to the crop. These became especially 

 abundant towards the end of the summer, a fact due, as it ap- 

 peared, to the great numbers of small apple-worms apparently be- 

 longing to a third generation. Even where these were killed by pro- 

 fuse and persistent spraying, they ate into the surface of the apple, 

 in getting their fatal dose of poison, sufficiently to blemish the 

 fruit and greatly to lessen its market value. The consequences 

 are thus described by Mr. R. A. Simpson, one of the most intelli- 

 gent and careful apple growers in the state, in a letter dated De- 

 cember 28, 1914: "We made a total failure this year in control- 

 ling the codling-moth, notwithstanding the fact that we sprayed six. 

 and in some cases seven, times. After the worms began to show up, 

 they seemed to come continually until fall, and practically all of 

 them entered the apple at the side. A single apple was often at- 

 tacked by many worms, sometimes as many as fifteen, and in one 

 case which I saw, twenty to the apple." 



These conditions called loudly for a reexamination of the life 

 history of the codling-moth in Illinois, and a more exact and com- 

 prehensive study of the subject than had ever been made in this 

 state. Plans were consequently laid last fall for a timely begin- 

 ning this year on a program of field observation and experiment 

 which should give us an accurate and detailed knowledge of the 

 life history of the pest for this season, and also of the weather con- 

 ditions which might be supposed to affect it in any way. This pro- 

 gram has now been carried thru in the most thorogoing manner at 

 Olney, where a completely equipped station was established last 

 April, and in a less elaborate way at Ozark, in Johnson county, at 



*The following article is an advance impression, only slightly changed to 

 adapt it to its present use, of a paper read to the State Horticultural Society at 

 its annual meeting December 17, 1915. 



