236 



THE CANADIAN ENTOMOLOGIST. 



One thing to be observed is usually the expulsion of a transparent drop of 



'•honeydew" from the very small anal 

 opening immediately beneath the base 

 of the Cauda. Waxy drops of white, 

 yellow, brown, red or the deepest 

 black fluid may usually be seen at the 

 same time as they are expelled from 

 the tips of the cornicles ; and the 

 embryos, the eggs, or the genital organ 

 of the male, as the case may be, will 

 be protruded from the large genital 

 opening beneath the anal plate. (See 

 figure.) 



Neither the writer nor his helpers, 

 who have been observing the Aphidid£e 

 rather carefully for a few years past, 

 have ever found "honeydew" issuing 

 from the cornicles. 

 There is properly but one anal and one genital plate, each beneath 

 the aperture named, as shown in the illustration. Or these plates might 

 be called supra- and infra-genital plates. And then the honeydew is 

 expelled with considerable force free from the body, while the sticky drops 

 that are expelled from the cornicles accumulate at their ends and may run 

 down, but do not often free themselves from the cornicles. It is probably 

 true that the exudation from the cornicles is somewhat protective. It is 

 difficult, however, to believe that this secretion can be very effectual in 

 defending the Aphididse from the attacks of their predaceous and para- 

 sitic enemies. 



In my observations the cornicles have always been found between 

 the 5th and 6th segments of the abdomen, or upon the 6th, but they have 

 not always been so drawn in published illustrations. 



Fig. 13.— Abdomen of Aphid. 



Explanation of Figure 13 : 

 Terminal joints of abdomen of Aphid showing drop of honey- 

 dew ; C, cornicle ; A, drop of sticky exudation at end of cornicle ; S, 

 style or cauda ; H, honeydew escaping from anal opening ; G, two 

 genital plates, between which is the genital opening. The superior of 

 these two plates is properly the anal, or supra-genital plate, and the lower 

 plate is properly the genital or subgenital plate. 



