16 



difficult to pierce with their delicate little beaks. A badly infested tree or branch 

 will become so thickly encrusted with the insects that the bark is completely con- 

 cealed. (See Fig. 2.) Such branches look as if they were covered with ashes. If 

 we cut through the bark obliquely we shall see that the tissue beneath even as far 

 as the outer sapwood is conspicuously colored purple. On young branches and 

 nursery stock there is frequently, but not always, a reddish area around where the 

 scale feeds. This helps the inspector to find the insect more easily. The skin of 

 the fruit, especially of apples and pears, is also conspicuously marked with these 

 red discolorations, which often make it easy to detect the presence of the scale 

 even without looking at the bark. On apples the insects are regularly most numerous 

 in the calyx and stem ends, probahly because these are more sheltered parts. Leaves, 

 though not so commonly attacked as fruit and bark, are often badly infested. 



^ «.f ^/^ 



Fig. 8. San Jose Scale on pear leaves and discolorations caused thereby, 

 natural size (after Lowe and Parrot). 



especially on the upper surface. The insect causes these also to become discolored. 



(See Fig. 8.) 



The injury done by San Jose Scale is caused by the millions, or more correctly 

 billions, of the little creatures sucking the juice out of the plant through their long, 

 delicate beaks, and thus starving the tree by depriving it of its food. It is claimed 

 that they also secrete a poison which increases the injury. Small trees may be 

 killed in a couple of years; larger trees usually take longer, and an old apple tree 

 may survive for six years or more, but ultimately will perish if not treated. The 

 same fate will befall any orchard once attacked and left unsprayed. In old trees 

 it is the outer branches that die first, and in putting a tree into shape to spray one 

 often finds it necessary to cut such branches back six feet or more to reach the 

 living parts. Infested fruit is usually dwarfed, and frequently there are small 

 depressions where the scale feeds, especially in the case of pears. Such fruit is 

 often almost worthless except to feed to stock, as it is illegal to sell it. 



