ENTOMOLOGICAL SOCIETY OF ONTARIO. 



81 



identification is, nevertheless, a matter of great importance because it has been found by 

 experience that neither of these scales causes very serious injury to fruit trees as compared 

 with the San Jose' scale. This is chiefly due to the fact that they seldom spread from 

 tree to tree with anything like the rapidity of the last named species. Indeed, the 

 occurrence in very large numbers of a scale insect upon a tree cannot always be taken as 

 conclusive evidence that the species is a dangerous one, for it has frequently been noticed 

 that scale insects may be present in enormons numbers upon a special tree, even killing 

 it, and yet not be found at all upon trees of the same sort growing close by. In the 

 case of the San Jose" scale, on the other hand, if other trees are reasonably near, it is 

 almost certain that they will soon become infested, and when a severe case of infestation 

 is found, one of the first things looked for when considering whether the pest is actually 

 the San Jose" scale or one of some other species which superficially resembles it closely, 

 is to notice whether the surrounding trees are infested also. 



This important difference of habit in spreading and the much more fatal effects upon 

 the trees from the presence of the San Jose" scale, make much more stringent measure 

 necessary to secure its eradication than with many other species, even frequently 

 rendering it advisable, or imperative, to destroy many trees, or even whole orchards. This 

 being the case, the very great advantage is obvious of being perfectly sure as to the 

 identity of an infesting scale insect before valuable trees are condemned to destruction. 



Fig 54. 



Appearance of scale on bark ; a, infested twig— natural size ; b, bark as it appears under hand 

 lens, showing scales m various stages of development and young larvae. 



The following description of the San Jose scale and its life history are taken from 

 the annual report of the Entomologist and Botanist of the Dominion Experimental 

 Farms for 1897 : 



How to know it. — The general appearance of the bark of infested trees is dirty, 

 scurfy and grayish in color, as though dusted with ashes. The scales usually are found 

 in enormous numbers, frequently overlapping or occurring altogether on the top of 

 older scales ; they may be found throughout the summer of all sizes, from the newly 



6 EN. 



