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words additional will serve for the less complete records at Ozark, 

 Plainview, and Princeton. Codling-moths were, however, so scarce 

 at the two latter points that they have given ns scanty material 

 for a reliable comparison of seasonal life histories. At Ozark we 

 found three generations of the codling-moth this year, the same as 

 at Olney ; but no trace of a third generation could be detected either 

 at Plainview or Princeton. At Ozark, apple-worms of the first 

 generation became full-grown and began to leave the apple ten 

 days before they did at Olney, at Plainview ten days later than at 

 Olney, and at Princeton fifteen days later than at Plainview. Ap- 

 ple-worms of the first generation hatched from the egg at Ozark 

 four days earlier than they did at Olney, those of the second gen- 

 eration nine days earlier, and those of the third generation thir- 

 teen days earlier, the differences between the generations at these 

 two places naturally increasing as the season went on. Indeed, the 

 several stages of the third generation made their appearance at 

 Ozark twelve days earlier, on an average, than they did at Olney, 

 and the numbers of this last generation, with this advantage of a 

 twelve-days' earlier start, must have become materially greater 

 before the season ended than at Olney, if conditions had been other- 

 wise substantially the same. We have not had time since the final 

 reports for the season came in to figure out the temperature records 

 for the substations at Ozark and Plainview, and hence we can not 

 show at present how these differences in life history are related 

 to differences in temperature. There is enough in our data from 

 different localities to show, however, that a single general program 

 or spraying calendar can not be made to fit the varying conditions 

 of the different parts of our Illinois fruit-districts, but that at 

 least three points of observation must be established if we are to 

 get the full benefit of what we can learn. When we are farther 

 along with this whole subject of inquiry it seems quite probable 

 that the weather records of the season, checked by some orchard 

 observations, will enable any well-informed man to judge the pro- 

 gress of the codling-moth in his orchard without precise observa- 

 tions on the insects themselves; at present, however, this is not 

 possible. 



Of course we well understand that the complex operations we 

 have been describing are quite impossible to the orchardist, and 

 must be carried on, if at all, by trained experts at stations prop- 

 erly equipped. What may the fruit-grower do, nevertheless, to 

 determine for himself when the larvae of the various generations 

 are to appear and when, consequently, his spraying operations 

 should be done? The adult moths, the eggs, and the young larvae 

 about to enter the apple are very difficult to find in an orchard 

 unless they are present in large numbers, but the moths are easily 



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