16 
localities the loss is almost total. Gaivia records, from check trees 
in si>rayiiig experiments, that the loss varied from 67 to 99 per cent. 
There are many localities in this zone in both east and west where 
apples can be grown, but on account of the injuries due to the codling 
moth other crops are grown instead. 
IMMUNE REGIONS. 
hi man}' regions of the Far West one often hears the fruit growers 
say that on account of the peculiar climatic conditions of that region 
apples are free from injui-y and the codling moth can not exist. 
Among these climatic conditions quoted are dense fogs, mountain 
breezes, and comparatively high altitudes. Seven or eight years ago it 
was thought that the Hood River Valley was immune from the insect; 
the same was thought of the Pajora Yallev in California; but later 
developments have shown that immunity was due to the fact that the 
insect had not been introduced into those localities. It has also been 
said that there was no codling moth near the coast in Oregon, but 
Professor Cordle^^ finds that it is present in some localities and 
believes that the former imnumit}^ was due to isolation. 
In many restricted areas in the Pacific Northwest more or less 
isolated the codling moth is either absent or present in such small 
numbers that it has not l)een observed. From past experience and 
examination of these localities it is evident that the insect in its gen- 
eral spread has not yet reached them. It is a question whether or 
not the insect will l)e injurious in these localities, but it is certain that 
it can be present. The writer has no hesitancv in concluding that 
there is no region in the Pacific Northwest in which apples are 
grown in which the codling moth can not exist. 
Many causes of immunity b}^ isolation in river valleys have been 
noted. The most marked case is at Mr. I. B. Perrine's orchard at 
Blue Lake, Idaho. The nearest orchard is IS miles distant down 
Snake River, while there are no orchards in the other direction inside 
of 75 to 80 miles. This orchard was free from codling moth until 
three or four years ago, the larvae having undoubtedly been intro- 
duced in old apple boxes about that time. 
MEANS OF SPREAD. 
There are several ways in which the codling moth can be distributed. 
The most prolific source of distribution comes from the shipping of 
fruit from an infested region. Fruit which contains the larval insects 
ma}^ be shipped great distances, and when the larvw complete their 
growth they spin cocoons, and in due time the moths emerge, and 
with unerring instinct seek the nearest apple trees. Many larvte are 
found to have spun their cocoons in the angles and cracks of the boxes 
