444 



AN INTRODUCTION TO ENTOMOLOGY 



New Zealand, but usually it is more or less reduced, consisting either 

 of two segments or of only one ; in a few subfamilies it is wanting 

 in the adult. The mandibular and maxillary setas are wanting in 

 the later nymphal instars of some forms, in some adult females, 

 and in all adult males. These . setae, when present, are usually 

 long, frequently longer than the body, and in some species sev- 

 eral times as long. When not exserted, they are coiled within- a 

 pouch, termed the crumena, only their united tips extending to the 

 labiimi. The crumena is a deep invagination of the body-wall, which 

 extends far back into the body-cavity. Its walls are delicate, and 

 not easily observed; but the coiled setae within it can be easily seen 

 in cleared specimens (Fig. 516, s). 



In the classification of coccids, the characters most used are those 

 presented by the female, although those of the male are used to some 

 extent. The most available characters of the female are the following : 

 first, the general form of the body; second, the form of the waxy 

 excretions; third, the structure of the caudal end of the body; and 

 fourth, the form and position of the pores through which the wax is 

 excreted. 



To study the third and fourth classes of characters listed above, 

 it is necessary to remove the wax, to clarify the body, and, in some 

 cases, to stain it. The method most commonly used for removing the 

 wax and clarifying the body is to boil the specimen in a ten per cent, 

 aqueous solution of caustic potash. For staining the body, Gage ('19) 

 found that a solution of saurefuchsin was most satisfactory; his 

 formula for the preparation of this solution is as follows : 



Saurefuchsin 0.5 gr. 



Hydrochloric acid, 10% 25.0 c.c. 



Distilled water 300.0 c.c. 



The cleaned and stained 

 specimens are usually mounted 

 in Canada balsam for micro- 

 scopic examination. 



Within the family Coccidae 

 there are to be found most re- 

 markable variations in struc- 

 ture; this is especially true of 

 the form of the caudal end of 

 the body and of the form of the 

 parts through which the wax 

 and other excretions are exud- 

 ed. Th ese characters have been 

 described by many authors; 

 but, unfortunately, there is a 

 great lack of uniformity in the 

 Fig. 517. — Caudal end of female of Eriococ- terminology used by them. 

 cus araucaricz: r^^nz\ ring;^, anal-ring j^^ ^-^is place, only sufficient 

 setae; /, anal lobe; as, anal seta. Be- u \i- 1 j. j ^ 



tween the bases of the anal-ring sets space can be taken to define 



there are openings of wax-glands. the more important Struc- 



