490 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



trees was surrounded by severely infested orange trees on the west, 

 south, and east sides. On the north was an abrupt slope of barren 

 ground. There were 25 trees north and south and 16 trees east and 

 west in the block. The examination for scales was made on August 

 20, 1915. Twenty-five leaves were selected at random from the north, 

 east, south, and west sides of the tree respectively, making a total of 

 100 leaves from each tree. 



Below is represented the block of trees on which examination of 



WIND DISPERSION 

 Young Black Scale. 



9 13 16 



Fig. 35. Data from experimental plot. (Original). 



young scales was made. The small figures represent the number of 

 scales on 25 leaves on the respective sides of the tree, while the large 

 number, which is the total of the small numbers, represents the number 

 of scales on 100 leaves of the respective trees. 



From the above it will be seen that there is a total of 4,803 scales on 

 100 leaves of every fourth tree on the west row, while the fifth row to the 

 east drops down to 1,564 scales, or a difTerence of 3,239. The first 



