i.s9(i. 1 35 



4. — The principal food-plant, as mentioned above, is the pear; when the peach is 



mentioned it is only incidentally, or as very slightly attacked. 

 5. — No mention is made by authors of the second female pellicle as being any larger 

 than the adult female. 

 Now, in all the foregoing characters, the specimens on which I 

 founded mj Aonidia fasca differ from Asp. perniciosus ; and if one 

 might accept as positively final the statement in " Insect Life " (vol. 

 vii, p. 289) that " the San Jose scale differs from all others in the 

 peculiar reddening effect which it produces," then there would be no 

 more to be said, for Aonidia fusca produces, so far as I know, no such 

 effect. In size A. fusca is much smaller, the female puparium having 

 a diameter of tV inch. In colour it is " very dark brown or dull 

 black." And again, A. fusca is decidedly numerous on peach twigs. 

 Lastly, the second female pellicle is larger than the adult insect. 



Judging, therefore, by all the external characters (except that of 

 the second pellicle, of which I find no record) Aonidia fusca is different 

 from Aspidiotus perniciosus. 



But a careful comparison of the adult female insects shows that, 

 with the exception of size, their characters are very similar. My 

 specimens of Asp. pe^'niciosus (originally received from Professor 

 Comstock) average aV inch in length; those of Aon. fusca average aV 

 inch. In colour the two agreej also in the absence of any groups o£ 

 " spinnerets ;" likewise in the terminal lobes, hairs and indentations 

 of the abdomen. The last two characters are of especial importance ; 

 so much so that I am strongly inclined to think that I made a mistake 

 in separating the two insects, at least specifically. The identity of my 

 Australian specimens of Aspid. perniciosus with those from America is 

 absolute; my Australian ^o«zJia is anatomically very close to both, 

 the principal differences being external. 



It remains to discuss the generic character of the comparative 

 dimensions of the adult female and the second pellicle ; a character 

 which distinguishes Aonidia from Aspidiotus. I have already remarked 

 that I find no notice on this point in any author as to A. perniciosus ; 

 but as regards ^i. /ms(?« I have no doubt, and I possess a mounted 

 specimen of an adult with the second pellicle still attached, the differ- 

 ence in size being perfectly clear ; the pellicle extends all round 

 beyond the adult. Assuming, therefore, that it may be necessary to 

 unite the two insects, and to make fusca a variety of perniciosus on 

 the ground of anatomical similarity, ignoring the external differences, 

 it will become a question then of removing perniciosus from the genus 

 Aspidiotus and of attaching it to the genus Aonidia. 



