2o6 THE ifODNG NATURALIST. [Noyembek 



A NOTE ON ZYGCENA EXULANS. 



BY W. H. TUGWELL, F.E.S. 



The description given of Zygcena exulans by Mr. C. W. Dale, 

 F.E.S., in his history of British Sphinges, now publishing in the 

 Young Naturalist, is rather meagre and overlooks a most essential 

 character of this rare and local species, viz., the great difference that 

 exists between the sexes. The male has the head, thorax, legs and 

 body of an uniform black colour and more or less covered with long 

 shaggy hairs, the forewings are semidiaphonous, thin in texture and 

 very sparsely covered with dark scales, which give a dark greenish 

 -black tone to the wings (rather than " bluish grey " as described by 

 Mr. Dale,) the nervures of the wing stand out distinctly darker like 

 pencilled lines. There are five dull crimson spots on each forewing 

 which varies not only in size but also much in colour of the spots, 

 a few are of a fairly bright crimson, but in the Braemar insect is 

 never anything nearly as brilliant as in the Swiss specimens, these are 

 always brighter coloured and more densely scaled than the Scotch insect. 

 The Scotch insect Zygcena exulans, var. subochracea White, this 

 colour is generally of a dull crimson, rather paler on the edges and 

 often passes into a dull ochreous grey, with hardly a tint of red about 

 it. Very rarely you meet with one in which the colour of forewings 

 inclines to a bluish colour with a slight bronzy tone about, but this is 

 quite an exception. A dull greenish black is certainly the type. 



The female differs most materially, the head is black, with a yellowish 

 white collar running over the front of the thorax, and the legs are all 

 yellowish white, with a few black hairs. The ground colour of the 

 wing is the same as the males, but the scales along and over the 

 nervures, are white or very pale, instead of being black as in the males ; 

 making the nervures to stand out conspicuously pale, giving them a 

 white appearance almost as if they had been dusted with flour. This 

 is very apparent in the living insect, perhaps less so after the insect is 

 set and dry, but it still remains as a most characteristic difference in 

 the two sexes. The hind wings in both sexes are the same and vary 

 much in tone of colour and in width of dark margin. This is often a mere 

 line on the fringe but in some it is fairly broad, occupying one third of 

 the area of the wing, and the colour, from a very dull crimson, to an 



