THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol.. XVIII. OCTOBER, 1896. No. 10 



The San Jose Scale. 



By chrysanthemum, 

 with frontispiece. 



This scale, which is now being distributed over widely 

 separated sections of the United States, was first noticed 

 in San Jose in 1893 and named " Aspidiotns pernicious." 

 Instead of being oblong, like most of our native scales it 

 is in general appearance nearly round and flat, of a dirty 

 gray color, with a black spot in the center. If the scales 

 are lifted with a knife the insect itself, if alive, will be 

 seen as a yellow speck, if dead it is usually brown in 

 color. It is about one-eighth inch in diameter and when 

 numerous give the tree the appearance of having been 

 washed with lime and soot. 



The life of this insect, with the exception of a few 

 hours of active larval existence, and an equally brief 

 winged existence in the mature male, is passed under the 

 protection of a waxy scale and under this tliey spend the 

 winter. Early in April the inales emerge, and by the 

 middle of May the over wintered females mature and be- 

 gin to give birth to living young. In this respect they 

 differ from most other scale insects. With the Oyster 

 Shell Bark Louse, if one of the scales be lifted, the shrive- 

 led body of the mother will be found in the more pointed 

 portion of the scale while the remainder will be filled with 

 eggs (figs. 1 and 2). This is also the case with the Scurfy 

 Bark Louse (figs. 3 and 4). Notice also the diff"erence in the 

 shape of the scales in each insect. Ordinarily eggs 



