.SCALE INSECTS OF IMPORTANCE 343 



TECHNICAL STUDY OF FOUR SPECIES OF ASPIDIOTUS 



BY MARGARET FURSMAN BOYNTON 

 PREFACE 



The four species ofAspidiotus, A. ancylus, A. forbesi, 

 A. ostreaeformis and A. p ernici osu s , are those most com- 

 monly found on fruit trees in New York state. They are closely related, 

 and all pass the winter as immature individuals, .Much of the inspection 

 of nursery stock is done either in the fall or in the early spring, and it fre- 

 quently happens that we are called on to identify a species from immature 

 specimens. It is very true that adults should be somewhere in the vicin- 

 ity of the young, but, as a matter of fact, it is frequently difficult to obtain a 

 satisfactory amount of adult material for study ; consequently it is quite 

 important that we be able to separate these species by characters found 

 in immature as well as adult specimens. A study of these species, with 

 directions to give special attention to the immature stages, was assigned 

 to my second assistant. Miss Boynton. The results are given in the fol- 

 lowing paper. 



E. P. Felt 



Explanation of terms. In the study of scale insects the final 

 appeal for the determination of species is, of course, to the microscopic 

 detail of the anal plate, made up of the terminal segments, of the adult 

 female. Here peculiar organs appear which are designated by distinctive 

 names, and must be recognized by the terms so used in order to under- 

 stand any technical description of species. It may be well to illustrate 

 with a diagram (pi. 11) and to explain those which occur in the following 

 characterizations, specially as the usage of these terms varies somewhat 

 with different writers. 



The margin of the anal plate is irregular, usually showing broad and 

 somewhat thickened prolongations of the body wall. These are called 

 lobes (pi. 1 1, fig. la). In the following species there are two or four, paired 

 bilaterally, as are most of the important organs on this segment, and 

 some times there are the rudiments of a third pair. It is supposed that they 

 are used in shifting the position of the insect under the scale. Spines and 

 plates also ornament the margin. The spines appear under the micro- 

 scope like short, stiff hairs with bulbous bases. They are likely to extend 

 more or less nearly at right angles to the general line oi the margin, are 

 similarly arranged on the two sides of the median line, and are usually on the 

 two surfaces, the dorsal and the ventral. That is, when the focus is fixed 



