Variation in. tlie Species of the scale ^"^ 



• XII. Variation in the Species of the scale. 



There is a considerable variation in the scale. The colours of male and 

 female scales vary according to the age of the individuals, the age of the hosb 

 and the place where the host grows ; the habits of the scale also differ more or 

 less under a given condition. So without a careful comparative study of a 

 large number of specimens one is very liable to fall into misconseption with 

 regard to the species. 



Prof. J. D. A. Cocke rell * has described two varieties or subspecies of 

 the San Jose Scale, Aspidiotus perniciosus, namely Andromelas and 

 Albopunctatus ; these specimens were obtained from A. Craw, San 

 Francisco, whose nursery stock introduced from Japan had been infested as 

 already mentioned. 



The professor has distinguished these species with the following 

 characters : — 



A. Male scale all black, the dot and ring not distinguished by colour, 

 but distinctly sculptured a Japanese species ; Andromelas 

 Ckll. 



B. Male scale grayish, hardly black with a light dot and ring ; 

 San Jose Scale, Aspidiotus pernioiosus Comst. 



C. Male scale grayish black, the light dot and ring very con- 

 spicuous ; occurs on orange or citrus trees and on plum trees 

 in Japan ; x\lbopunctatus Ckll. 



From the fact that there had been found two subspecies of the San -Jose 

 Scale in Japan Prof. Cockerell says f " Ir, is now to be shown for the first 

 time that A. perniciosus is, with little or no doubt, a native of Japan ; for 

 in Japan there occur two varieties or subspecies of A. perniciosus : 

 Andromelas and Albopunctatus. These agree almost exactly in structural 

 forms with Perniciosus, but the first differs noticeably in the colour of the 

 scale, the second slightly in the scale and more noticeably in attacking 

 citrus." As shown by the professor they are plainly different from the true 



* Technical ser. No. 6, U. S. Department of agriculture, Division of entomology, 1897. 

 t J. S. No. 6, 



