1882.1 179 



gating it from time to time for a dozen years, and am not fully satisfied 

 yet. The distinctive characters, as given by Mr. Stainton, are : the 

 dark clouding on the costa, and the short black streak on the anterior 

 lobe of the fore-wing. 



This insect is common in chalky places among Scabiosa columbaria 

 — sometimes swarming about disused chalk-pits, — from nine to ten 

 lines in expanse of wings, usually with the markings more or less 

 distinct, and sometimes very pronounced, but also frequently varying 

 in the direction of faintness of these typical markings until in some 

 specimens they entirely disappear. On the other hand, we find 

 scattered all over the country, almost wherever Scabiosa succisa grows, 

 the ordinary M. bipunctidactylus, varying from eight to ten lines, the 

 smallest specimens generally occurring in the drier localities, where 

 the scabious is stunted. These are usually without the clouded costa 

 and black streak on the anterior lobe, but in some specimens both 

 characters appear indistinctly, and, in some few, they are to be seen 

 pretty distinctly ; in fact, the two forms distinctly overlap. I remem- 

 ber that at Ranworth Fen a patch of very luxuriant Scabiosa succisa 

 produced specimens that leaned altogether to the plagiodactylus form ; 

 while at Brandon, among Scabiosa columbaria and arvensis, the two 

 forms were so mingled, that no one could separate them. Now, in all 

 these forms the black spot before the fissure is constantly present, it 

 does not seem in the least degree to share in the inconstancy of the 

 other dark markings, and the white border of the fissure is also 

 usually visible. 



From the lake district comes a form in which these reliable 

 characters are much as usual, but the variable characters — the clouding 

 and black streak — are so much exaggerated that the insect has been 

 described as a distinct species. It has, however, been reared from 

 precisely similar larvaB to those of plagiodactylus, feeding in a precisely 

 similar way. I have many times spent hours — with good magnifiers 

 — over long series of these various forms, and have not been able to 

 find any reliable point of distinction between them, and the only 

 logical conclusion I can come to is, that they constitute but one species 

 ■ — bipunctidactylus, of Haworth. As already stated, I believe the few 

 British specimens that have been reared under the name of aridus, Z., 

 to be pale ochreous varieties of this species. I will not venture an 

 opinion upon Zeller's aridus, of which I have but a single type, and 

 which is recorded from Southern Europe, Northern and Western 

 Russia, Armenia, and Palestine. 



The larva of M. plagiodactylus, with its mode of feeding in the 



