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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
miscible oils. The average value of fruit for well-cared for orchards is 
$1.00 per bushel, which will give us an average value of the crop for a 
twenty year old tree as $12.00. Thus we might figure the annual loss 
where scales are sufficiently abundant to badly spot fruit as about 
$252.00 per acre. The weakened effect, before and after control, may 
result in an average of four years unproductiveness, amounting to a 
monetary crop loss of $1,008.00 per acre. These figures should be 
sufficient to suggest a basis for estimating monetary losses from the San 
Jose scale under varying conditions and degrees of injury. 
We recognize the injury and financial loss that may result from San 
Jose scale but it is more difficult to estimate the abundance and degree of 
infestation. As a matter of fact, the degree of infestation is less signifi¬ 
cant inasmuch as other factors, such as location, vigor of tree and 
varieties enter into the problem in a material way. This is not true of 
course in estimating the value of insecticide treatments and the ideas 
which we are going to express have a more direct bearing on that feature 
of our work. 
No exact rules can be given for determining abundance. Estimations 
are only approximate and the relative value of figures or degrees of in¬ 
festation will vary with the individual making the records. 
Methods of determining the value of insecticide treatments by 
relative abundance of the scale offer a means of estimating the abund¬ 
ance of an insect. These methods which were used as a whole or in 
part, for determining the value of insecticide treatment, by W. P. 
Flint in Illinois, J. J. Culver in several states and the writer in Indiana 
are, briefly, as follows: 
Previous to treatments the infestation is estimated. The degrees are 
specified as 'very slight where only an occasional scale could be found, 
slight where scales were not common but could be located without 
difficulty, moderate where scales were fairly common and nearing an 
encrusted condition, heavy where the scale was doing noticeable injury 
and where occassional limbs were encrusted, and heavy encrusted where 
many branches were encrusted. In other words the degree of infestation 
was gauged from one to ten, a number one infestation being very slight 
and ten the heavv encrusted condition. At the same time this infes- 
j 
tation was estimated, 500 scales from at least a half dozen twigs from 
different parts of the tree or trees, were examined under a binocular 
microscope to determine the percentage of dead and live scales. In 
making counts on apple it was found desirable to use one and two-year 
wood. 
