82 THE CANADIAN ENTOMOLOGIST. 



NOTES ON THE EXTERNAL CHARACTERS OF THE SAN 

 JOSE SCALE, CHERRY SCALE, AND PUTNAM'S SCALE. 



BY W. G. JOHNSON, COLLEGE PARK, MARYLAND. 



March 14th, 1898. — During the last two or three weeks, I have 

 received inquiries from Georgia, Iowa, Kansas, and Canada, regarding 

 the structural external characters of the San Jose scale ( Aspidiotus 

 perniciosus), Cherry scale (A. Forbesi), and Putnam's scale (A. ancylus). 

 I present, therefore^ a few notes on these species, which I hope may be 

 of some use to my fellow workers. 



It is not a very difhcult matter at this time of the year to separate 

 these species at a glance. As is well known, per7iiciosus winters as a 

 partially matured insect, and when the insects are perfectly normal, they 

 are almost always uniformly blackish, with the exuvise or nipple-like 

 prominences, very conspicuously surrounded by a circle, of the same 

 general colour, as a rule, as the rest of the scale. Of course, on trees 

 badly infested with this insect, there are always many scales of the old 

 males, females, and young, which were not sufficiently covered to protect 

 them at the time cold weather set in ; but where a sufficient number of 

 young in good condition can be found, the above character does not vary 

 much, and rarely, if ever, are the pup;^ of the males to be found at this 

 time of the year. 



Forbesi also winters in a partially matured condition, but male pupae 

 are conspicuously present at this season, or even very much earlier. 

 The colour of the scales varies considerably, but usually conforms some- 

 what to the colour of the bark. The nipple-like prominence is very con- 

 spicuous and is of an orange, brick-red or purplish tinge. The exuviae 

 are usually covered with a delicate film or membrane of rather light 

 colour, but are ruptured in most cases, exposing the bright coloured 

 centres. The scales of the males and females are not uniform in colour, 

 being much lighter around the border of the young female and at the 

 caudal end of the male scale. The conspicuousness of the exuvise and 

 the presence of the pupse at this time of the year are characters which 

 almost always distinguish this species ixom. perniciosus. 



The female of ancyhis, in this location at this season, is much 

 more developed than either of the foregoing species. The young females 

 are usually not so convex as perniciosus or Forbesi. The exuvii* are 

 lighter than perniciosus, and not nearly so bright as in Forbesi, varying in 



