ENEMIES OF APHIDES, 255 



some writers have escaped my own observations ; but the analogy 

 which the organs present to those of other insects renders their 

 existence pretty certain. The male generative organs may, in a 

 good specimen, sometimes be traced lying along the central part 

 of the abdomen, and consist of testes with subsidiary glands, and 

 a narrow canal with an ejaculatory duct ; but the parts are so 

 fragile and difficult to observe in juxtaposition that I could not 

 make a reliable drawing. The remaining internal organs follow 

 closely the lines found in other nearly related insects, and do not 

 present many features of special interest. 



The second aphidivorous genus of the CapsidcB is Plagio- 

 nathus (Fieb.), which includes nine species found in Britain. 

 Several of them are figured on PI. XIII., and it will probably be 

 found that most of them are occasional, if not habitual, Aphis- 

 eaters. They are generally narrow and oblong, and are distin- 

 guished from other genera, having a similar hook-like projection of 

 the nervure in the membranous wing, by the presence of all the 

 following features : — The tapering antennse, black or dark-brown 

 spots or spines, or both, on tibise, and a glistening surface clothed 

 with short, fine black or silvery hairs. 



The species are very widely distributed, and some, including 

 P. arbtistorum, the known aphis-eating variety, are very common. 

 P. arbustorum may often be found upon nettles, but wild cornel, 

 angelica, red currant, and rose, at times all become its temporary 

 habitat, and probably many other aphis-haunted plants are visited 

 by it. Mr. Watkins has communicated to me his observation of 

 the presence of the imago on Angelica in mid-winter, and there is 

 no doubt that it frequently hybernates in sheltered situations. The 

 aspect of the insect varies very considerably, it being variously 

 described as ranging from almost wholly black to dull yellow. I 

 have myself seen none but ochreous yellow specimens, some 

 having more black than others ; but in all, the black margins of the 

 light-coloured femora and two first antennal joints suffice to iden- 

 tify the species. 



Mr. Saunders tabulates the species as follows : — 

 I, — Vertex with a distinctly raised carina, antennse 

 short, with second joint longer than third and 

 fourth together ... ... ... Roseri. 



