PLANTING AND CARE OF TREES 



167 



feed upon the juices of the plant. There are two broods in a 

 season and infested trees soon present an unsightly appearance. 



Spraying with kerosene emulsion late in April to kill the adult 

 insects, is usually recommended. Some claim that spraying with 

 whale-oil soap, one pound to two gallons of water, gives better 



Fig. 



The work of the Spruce Gall-louse. 



results. AVhatever is used it should be applied before the galls 

 are formed. On small trees the pest may be kept under control 

 by cutting out and burning the galls as soon as they are formed 

 and while the insects are within. 



Scale Insects — The most destructive forms of scale insects are 

 the cottony maple scale, the woolly maple scale, the San Jose 

 scale, the oyster-sliell scale, the scurfy scale, and the tulip scale. 

 They are all small and some of them are so inconspicuous as to 

 go unnoticed until much damage has been done. The young 

 insects, as a rule, are active only during the first few days of 

 their life, after which they settle down, project their beak into the 

 bark, leaf, or fruit and remain there for the rest of their lives. 



