119 



duction of its numbers and to the exclusion of the scale from new 

 g-rounds rather than to its complete extermination on his premises. 

 Stock badly infested by it should be thrown aside, and care should 

 be exercised in establishing- new plantations that they are not adja- 

 cent to infested trees. As it spreads only by the locomotion of its 

 minute young-, aided rarely by nesting birds, and as its active period 

 is limited to a very few days after hatching, it does not readily spread 

 to any considerable distance, and a new plantation can be kept free 

 from it if some thought is given to the matter in the beginning. 



The Oyster-shell Scale. 

 ( Mytilaspis pomortmi. ) 

 The scale generally known by the above common name is so 



A l^M ^^^^^^ because of 



its whimsical re- 

 semblance to half 

 an oyster - shell. 

 (Fig. 9.) It is 

 about a sixth of an 

 inch long, brown- 

 ish, or grayish, 

 colored about like 

 the bark of a tree, 

 not flattened like 

 the scurfy scale, 

 but convex from 

 side to side, and 

 two or three times 

 as long as wide. 

 The eggs under 

 the scale — to be 

 found to the num- 

 ber of a hundred 



or more at all times 

 Fig. 9. The Oyster-shell Scale: a, female scale, r xi. • + 



under side, showing the insect and its eggs within ; 



i>, same, from above; c, same, natural size; ^, e, male G^-f^y Spring are 

 scale, enlarged and exact size. (Howard, U. S. white or yellow- 

 Uept. of Agriculture.) ish, and not red 



like those of the scurfy scale. 



It is less generally distributed in Illinois than the scurfy scale, 

 and is, on the whole, somewhat more injurious when it becomes 

 abundant. It is relatively rare in nurseries except on overgrown 

 and neglected stock. Trees infested by this scale should not be 



