21 



of this species under a compound microscope I saw her produce a living 

 young-. It would be interesting* to ascertain if the same species can 

 be both oviparous and viviparous, but my subsequent notes on this 

 species are silent on this subject. 



Although I have repeatedly inclosed specimens of this species in 

 boxes I have never succeeded in obtaining any internal parasites from 

 them, nor can I find any published reference to parasites having been 

 bred from scales of this kind. 



The San Jose Scale. 



(Aspidiotus perniciosus Comst.) 



This is by far the most destructive scale-insect with which growers 

 of deciduous fruit trees have to contend. Its origin is uncertain, but 

 the fact of its being so frequently found upon plants imported from 

 Japan would seem to point to that country as the home of this pest. 

 The name of San Jose Scale was first applied to this species by the late 

 Matthew Oooke, from having first received specimeus of it from the 

 neighborhood of the city by that name in Santa Clara County. It is 

 to be regretted that any locality should be thus stigmatized by having 

 its name applied to a pestiferous scale-insect, and it would have been 

 far better had the later name of Pernicious Scale, first applied to this 

 species by the former entomologist of this Department, been adopted. 

 However, with the late Asa Gray, I do not consider it advisable to 

 change old names. 



This scale insect never attacks citrus nor coniferous trees so far as I 

 am aware. I have examined full-grown specimens upon the following 

 trees : 



Pear, Prune, 



Peach, English Walnut, 



Almond, Euonymus, 



Apple, And other ornamental shrubs. 



The specimens from English walnut were received from Mr. Henry H. 

 Wheeler, a prominent fruit-grower of Pomona, who writes me that he 

 has also found specimens of this species on almond trees. 



This is the only scale-insect known to me that causes a red spot to 

 appear upon the fruit or green bark which it infests. This discolora- 

 tion is usually attributed to the saliva with which the scale-insect 

 dilutes the sap of the infested tree or fruit, but why this should pro- 

 duce such a discoloration in the case of the present species but not in 

 that of any other species is no easy matter to explain. It need not be 

 taken for granted, however, that the saliva of all the different species 

 is identical in its composition. That of the present species may pos- 

 sess some peculiar, irritating principal which does not exist in the 

 saliva of any of the other species, and therefore the effects of the 

 attacks would not be the same in the different species. 



