34 THE SAN JOSE OR CHINESE SCALE. 



drawn. Special topographical conditions and protecting mountains 

 will probabl}^ account for other divergences. 



In the lower austral and tropical regions the San Jose scale, as 

 pointed out by Doctor Howard, may not prove as injurious as in the 

 upper austral, and this follows the general rule regarding armored 

 scale insects in warm countries. Armored scales rarely appear or 

 thrive in the moist Tropics, as shown by the explorations of the writer 

 in the East and West Indies. Fungous diseases, which thrive in warm 

 and moist climates, are the principal agency in keeping such scale 

 insects in check, and in the case of the San Jose scale the common 

 scale fungus Sphmrostllhe coccophila has alread}^ done good work in 

 Florida and other portions of the lower austral zone. Moisture is a 

 prerequisite in the case of this disease, and little benefit comes from 

 it in the drier portions of this zone. Too much stress, however, should 

 not be put on zonal limitations, and there may always be outbreaks 

 of longer or shorter standing in the borders of the transition region. 



HABITS AND LIFE HISTORY. 

 NATURE OF THE DAMAGE. 



The San flose scale, as already stated, occurs on all parts of the 

 plant— limbs (PI. I; PI. VI, fig. 1), leaves, and fruit (PL VI, fig. 2). 

 As the plant becomes badly infested the scales lie ver}- close together 

 on the limbs, frequently overlapping, sometimes with several young 

 ones clustering over the surface of an old mature scale. The gen- 

 eral appearance which they present is of a grayish, ver}^ slightly 

 roughened, scurf}^ deposit. The natural rich reddish color of the 

 3^oiuig lim])s of peach, pear, and apple is quite obscured when these 

 trees are thickly infested, and the}^ have then every appearance of 

 l)eing coated with ashes. When the scales are crusht by scraping, 

 a yellowish, oily liquid will appear, resulting from the mashing of 

 the soft, yellow insects beneath the scales. Examined under a hand 

 lens during the summer, numbers of the little orange-colored larva? 

 will be seen running about, and the snowy w^hite 3"oung scales will be 

 interspersed with the old brown or blackened mature scales. The 

 appearance presented at this time under the lens is shown in fig. 2. 

 Very frequenth^ the scale has a marked tendency to infest the extrem- 

 ities of the branches and twigs. This is particularly noticeable with 

 pear. As usually found on peach, the scale is massed often more 

 densely on the older growth, and works out more slowly toward the 

 new wood. 



The leaves are much less apt to bear scales, but in severe cases the 

 upper surface particularl}" becomes infested, the scales frequenth^ rang- 

 ing in two or more quite regular rows on either side of the midrib. 



