220 NATURE STUDY AND LIFE 



growth and little for life. As with the oyster-shell bark 

 louse, the young crawl actively about for a short time 

 after birth, and, since there are many generations, they 

 flow up over the new growth, leaves, and fruit of the 

 infested plant. The tree assumes the appearance of 

 being dusted over with ashes, and each speck represents 

 a tiny pump sucking its life sap. 



The danger from the San Jose scale is further enhanced 

 by the great number of its food plants. It seems to thrive 

 about equally well on the apple, apricot, cherry, currant, 

 gooseberry, cotoneaster, hawthorn, peach, plum, pear, 

 quince, rose, raspberry, spiraea, flowering quince, almond, 

 euonymus, linden, flowering currant, acacia, persimmon, 

 elm, osage orange, English walnut, pecan, alder, weeping 

 willow, and laurel-leaved willow, and even this list is prob- 

 ably far from complete. Infested trees, if left to them- 

 selves, commonly die within a few years. Young peach 

 trees may survive two or three years ; older and hardier 

 varieties, somewhat longer. Aside from injury by loss of 

 sap the San Jose scale appears to poison the plant, and 

 while there are two small, comparatively harmless, circular 

 scales, which cannot be distinguished from it by the unaided 

 eye, the sickly condition of the affected plant is generally 

 a sign that we have to do with the pernicious scale. 



If the San Jose scale is found, be careful to mount 

 some permanently for the school collection and send a 

 few twigs bearing specimens to the Agricultural Experi- 

 ment Station of your state, with an exact statement of 

 where they were found. Be sure that none of the speci- 

 mens are alive. They should be held in boiling water for 

 five minutes or left in a cyanide bottle over night before 



