98 



The statement is frequently made that the forests are full of 

 the scale, but this is a mistake. It will be seen from the above lists 

 that many forest trees are not liable to attack, and few of those that 

 are so, will support the scale in any considerable numbers. Our native 

 dogwoods are apparently less subject to infestation than some of the 

 imported species. Wild crab-apple and hawthorn and a few of the 

 other more or less susceptible trees and shrubs are likely to become 

 infested when growing near orchards, and it is possible that in some 

 localities these susceptible species are harboring the scale in forests. 



Osage orange hedges are very apt to become heavily infested and 

 form great highways for the dispersal of the scale. They should there- 

 fore be grubbed out or kept trimmed so low that they may be thoroly 

 sprayed. 



Means of Distribution 



By Birds, Squirrels, Insects, Wind, etc. — It is only while in the 

 crawling stage, during the first few hours of its life, that the San 

 Jose scale can be transferred from one food plant to another, because 

 as soon as it begins to feed it becomes fixed to the bark for the rest 

 of its life. In most cases the young do not travel more than a few 

 inches from the place of their birth ; and one part of a tree may con- 

 sequently become heavily infested while another part is comparatively 

 clear. The larv^ can not pass from tree to tree unaided unless the 

 twigs touch or the trees stand very close together, as in the nursery 

 row; but they may be carried to neighboring trees by a variety of 

 agencies, the principal of which are birds, squirrels, insects, men, do- 

 mestic animals, and the wind. They may also be carried on fruit or 

 on cuttings from trees. In this way they pass from tree to tree and 

 from orchard to orchard. In communities where orchards are close 

 together, the scale may spread from a single center over a very large 

 area in the course of a few years. In towns, also, it gradually extendi 

 its range until all premises become infested. 



The rate at which it spreads depends, of course, upon the num- 

 ber of crawling young. When nothing is done to keep them down, 

 they become very numerous, and every bird or insect that flies from 

 a tree so infested may carry some of them with it, and drop them, 

 perhaps, many rods, or even miles, away. But when the number of 

 young is kept down by proper treatment, their dissemination is corre- 

 spondingly slow. In farming communities where the orchards are 

 small and half a mile or more apart, there is little danger that the scale 

 will be carried from one to another if hedges are removed or cared 

 for and if proper methods of control are used. 



