51 



REPORT UPON AN INVESTIGATION OF THE CODLING MOTH IN 



IDAHO IN 1900. 



By C. B. Simpson, Special Agent. 



The following report upon an investigation of the codling moth in 

 the State of Idaho is made in accordance with the authorization of the 

 Secretary of Agriculture and instructions of the Chief of the Division 

 of Entomology: 



Upon reaching Boise I commenced a rigid inspection of orchards in 

 that vicinuvy and observed the methods used against the codling moth 

 and the results of the same. Numerous cages were started for the 

 study of the life history of the insect. Many articles upon the insect 

 were published in the leading papers. These articles were copied by 

 many of the other papers. I also had a long conference with Professor 

 Aldrich, of the University of Idaho, in regard to the codling moth. 



EXTENT OF INJURY. 



Indications of damage caused by the codling moth were seen in every 

 section of the State which I visited where apples are grown. By 

 report the moth is present all over the State, except in a few limited 

 localities in the mountains. From my observation I can say without 

 hesitation that 50 per cent of the apple crop of Idaho was destroyed 

 by the codling moth in 1900. According to Mr. McPherson the loss 

 in South Idaho and about Lewiston for the districts was 75 per cent. 



In untreated orchards I found a great difference in the percentage 

 of apples infested. The injury ranged from 40 per cent to practically 

 100 per cent. In the small orchards and isolated trees in and about 

 Boise I have been unable to find sound apples. In the larger untreated 

 orchards which were more or less isolated I found in some cases the 

 injury to be about 40 per cent. In orchards well cared for I estimated 

 the injuries to vary from 50 to 0.05 per cent. In an orchard near 

 Boise that was sprayed and banded 44 per cent of the crop was lost. 

 In an orchard in the city of Boise that was sprayed with arsenites and 

 banded the loss was only about 20 per cent. In more or less isolated 

 orchards that were well cared for the loss was found to be 10 per cent 

 or less. In another orchard near Boise which had been sprayed three 

 times and no,t banded the injury was from 90 to 98 per cent. In an 

 orchard that was only banded the injuiy was about 60 per cent. 



About Lewiston the damage is somewhat less than in the southern 

 part. Professor Aldrich tells me that in 1899 the damage about Mos- 

 cow was 21 per cent, while in 1900 it was only about 10 per cent. 



I have been informed that in small valleys in the mountains the 

 codling moth does no damage. The apple is the fruit most infested. 

 The injury to pears never exceeds 0.05 to 10 per cent. 



