June, '17] FERRIS: STUDY OF MEALY-BUGS 323 



and present no stable characters upon which determinations may be 

 based. As a matter of fact such a conclusion is very far indeed 

 from the actual facts. 



The second factor, and that with which this paper is really concerned, 

 lies in the lack of a satisfactory technique for the preparations of 

 specimens for study. The usual method has been to clear the speci- 

 mens in caustic potash and then to mount in balsam or to mount in 

 balsam without clearing, the results in either case not being especially 

 fortunate. In some cases the specimens become so clear that it is 

 even difficult to find them on the slide and in no case can anything 

 more than the antennae and legs be seen without an inordinate amount 

 of eyestraining. In nearly all cases the characters that are actually of 

 the greatest value can not be seen at all. Because of all this, determina- 

 tions made by the comparison of specimens with types are frequently 

 no more to be relied upon than those made upon the basis of the litera- 

 ture. 



The solution of the difficulty lies in the utilization of a means of 

 staining the specimens in order to accentuate the characters that are 

 of especial importance. This is a method that has not usually been 

 popular, probably in part because the methods usually recommended 

 are more or less time consuming and in part because it has not really 

 been showm that these methods produce results of any especial value. 



For the staining of coccid preparations in general and for the par- 

 ticular method here advocated the author claims no originality what- 

 soever. It is believed, however, that it has not before been asserted 

 that for the satisfactory study of mealy-bugs and their allies the use 

 of properly stained preparations is not only desirable but is in fact 

 necessary. It is the non-use of such methods that has previously 

 prevented at least one author from producing results that would have 

 rendered the present paper entirely unnecessary. 



The method used has been essentially that recommended by Staf- 

 ford^ for use with Diaspine scales, but with modifications chiefly 

 directed toward a general reduction in the amount of time consumed. 

 It is applicable to other insects than coccids for it has proven eminently 

 satisfactory for use with certain aphids, particularly Chermes and 

 Phylloxera, and with the larvae of Cecidomjadae. The stain used is 

 Magenta Red and may be purchased in liquid form. It should be 

 diluted to one-half or one-fourth its original strength with water when 

 used. 



In its essentials the method is extremely simple. The specimens to 

 be prepared are boiled in caustic potash in the usual manner and then 



^Stafford, E. W. Studies in Diaspinine Pygidia. Annals Entomological Society 

 of America, vol. 8, pp. 67-73. (1915.) 



