THE CODLIN MOTH IN IDAHO IN 1000. 



815 



From the preceding record, from that of Professor Aldrich taken at 

 Juliaetta for 1899, and my own I have compiled the following table : — 





18'J7 



1898 



1899 



1900 



First brood : — 













Maximum 



July 10 



July 18 



July 



21 



July 15 



Minimum 



Aug. '.) 



Aug. 10 



Aug. 



12 



Aug. 4 



Second brood : — 













Maximum 



Sept. 2 



Aug. 31 



Aug. 



18 



Aug. 25 



Minimum 



Sept. 10 



Sept. 7 



Sept. 



4 



Sept. 1 



Third brood : — 













Maximum 



Oct. 4 



Sept. 22 



Sept. 



25 



Sept. 25 



Minimum 













From these records, supplemented by observation, I can say definitely 

 that there are three broods in the vicinity of Boise and the greater part 

 of the Snake River valley. 



As to the fourth brood I have no definite information at hand. Several 

 growers have told me that such a brood exists in part. At certain 

 periods it is impossible to say to what brood an insect belongs. For 

 instance, in 1900, if a half -grown larva was found October 4 it would be 

 impossible to know whether it was the last of the third or the first of the 

 fourth. When cold weather comes, there are many interesting things 

 apparent. If young larvae are left in the fruit on the ground, they 

 evidently perish. However, if taken inside with the apples they complete 

 their development, and if not destroyed insure a crop of moths for the 

 following spring. About September 5 it was noticed that the larvae that 

 had spun cocoons were not transforming, but were still in the larval state, 

 while those that had reached the pupa state were developing slowly and 

 the moths were emerging. It is evident that it takes a higher tem- 

 perature for the insect to change from larva to pupa than from pupa to 

 adult. 



Moisture and Heat. 



There is great mortality among the eggs of this insect, the direct rays 

 of the hot sun causing many to die. 



In the larval state, especially when young, there are many agencies of 

 destruction. I have found tips of branches upon which there was but one 

 apple. On the leaves near by there were half a dozen or so hatched eggs, 

 while the apple contained but one larva. In one case the larva would 

 have to crawl 20 feet before finding another. 



In many cases I have found from 2 to 5 per cent, of the larvj^ dead 

 before they had commenced their burrow to the centre of the apple from 

 the mine under the skin. There are very few deaths due to fungus and 

 bacteria in the dry regions. In many orchards, in which the water used 

 for irrigation is allowed to stand around the trees, the number of infested 

 apples is markedly less than in those orchards where irrigation is by 

 ditches. Also one does not, as a general rule, find as many worms under 

 bands on trees which have moist soil around them. The only explana- 

 tion is that the moisture either causes the insects to die by fungus or 

 bacteria or to seek other places. This method, however, has grave 



