where there are three, gives the time when the largest numbers 

 actually appeared, the other dates in this column being those when 

 the numbers were smaller, but still relatively large. 



Seasonal History of the Codling-moth as Observed at Olnet, III., in 1915 



Number 

 of gen- 

 eration 



Stages of development 



Dates of appearance 



Earliest 



Maximum 



Latest 



First 



Pupation 



Emergence of moths 

 Egg-laying 

 Hatching of larvse 

 Larva? leaving apples 



Apr. 

 > j 



May 



} } 



June 



7* 

 27 

 5 



17 

 12 



Apr. 19-26-May 4 

 May 10-15-22 



* " 16-31 



*May 26-June 12 



June 19-25-July 7 



June 



1 > 



July 



Aug. 



2 



24 

 30* 



9* 



9 



Second 



Pupation June 

 Emergence of moths 

 Egg-laying July 

 Hatching of larvae 

 Larva? leaving apples A no-. 



17 

 28 

 3 

 11 



2 



June 25-29-July 10 

 " 10-12-July 22 



* ' ' 19-July 28 



* " 19-Aug. 3 

 Aug. 18-Sept. 17-20 



Aug. 

 Sept. 



17 

 6 

 12 

 17 

 ... + 











Third 



Pupation 



Emergence of moths 

 Egg-laying 

 Hatching of larva? 

 Larva? leaving apples 



Aug. 

 Sept. 



3 



16 

 22 

 29 



90 





Aug. 

 Sept, 



18} [30] 

 5* [16] 

 14} [26] 

 19| [Oct. 7] 



.. . + 











*Dates computed. 



t Larva? were collected Nov. 1, the date when observations ceased. 



t These dates are for material collected from cages, but larva? from the much 

 larger band collections continued to pupate until August 30, and moths to emerge 

 until September 16. No doubt egg-laying continued to about September 26, and 

 hatching of larva? until about October 7. 



The part of this history which . especially interests the apple- 

 grower is the time of the hatching of the larvae of the successive 

 generations, because upon this depends the time when he must spray 

 to destroy them. Referring to our diagram we see that the first 

 generation of larvae hatched from the egg this year during the lat- 

 ter half of May and the whole of June but in much the largest 

 numbers during the first few days of June, that the second genera- 

 tion of larvae began to appear before the middle of July, that the 

 largest numbers of this generation hatched from the middle to 

 the end of that month, and that hatching continued during the 

 greater part of August. Practically all of the larvae of the last 

 generation hatched from the egg in September. It follows from 

 this that an insecticide spray applied to catch these successive gen- 

 erations should have been on the trees this year by the middle of 

 May for the first generation, before the middle of July for the 

 second, and about the end of August, if necessary, for the third. 

 Whether each or any of these sprayings, so applied as to be effective 

 when the first larvae of a generation begin to hatch, should be fol- 

 lowed by a second spraying when the larvae are hatching in the 



