largest numbers — in a fortnight, that is, after the first — will de- 

 pend in part on the number of the codling-moths infesting the 

 apple that year, and in part on the character of the season, and 

 the length of time during which the sprayed apples may continue 

 effectively poisoned. From the fifth line of our diagram we see 

 that we can not distinguish the second and third generations of 

 the larvae with regard to the times when they left the apple. As 

 a matter of fact, most of these represented by our diagram were 

 second-generation apple-worms, only a small percentage of which 

 changed to the pupa, the remainder going into hibernation as larvae 

 to pupate next spring. 



We may use this diagram in another way by following each 

 generation of the season obliquely from above downwards thru its 

 successive stages, beginning with the figure at the upper left-hand 

 corner, passing to the moth period below and to the right, and so 

 on down. By this means we see that the first generation of the 

 year, beginning as pupae in April and May, became moths in May 

 and early June, laid its eggs a little later in each month, its larvae 

 hatching from the eggs mainly in the first half of June, and emerg- 

 ing from the apple during the last half of June and the whole of 

 July. A similar use of the diagram will give the history of each of 

 the other generations in the same order. 



We have next to give especial and careful attention to the ups 

 and downs of the lower figure, representing the rise and fall of tem- 

 perature during the season, for comparison with the ups and downs 

 of the life-history figures on the same dates. We see, for instance, 

 that from its beginning in April, pupation jumps upward with the 

 rise in temperature, declines as that falls, reaches. its minimum at 

 the time of the lowest temperatures, starts upward when tempera- 

 tures rise again, and falls finally with the drop in the thermometer 

 to its minimum for that time of the year. 



We see this correspondence of temperature and life history 

 still more strikingly shown in the emergence of the first generation 

 of the moths, which made a slow beginning on a falling tempera- 

 ture, shot suddenly upward in two successive jumps with corres- 

 ponding rises in the thermometer, dropped to a standstill when 

 the thermometer fell to 51 degrees, rose again suddenly as the 

 temperature went up to 67 degrees, and then fell away to a finish. 

 The egg-laying period and the hatching period of this first genera- 

 tion are similarly but not so strikingly influenced by the weather 

 changes. In July, when the means of temperature ranged from 70 

 degrees to 82 degrees, and none were lower than 67 degrees, we 

 see less marked relation between temperatures and life histories, 

 altho even here the rise and fall of the thermometer is not without 

 its effect. The fall, for example, during the first week of July is 



