MELANISM IN YORKSHIRE LEPIDOPPERA. S2t 



such it was afterwards named, is to-day one of the greatest prizes a 

 lepidopterist can obtain. 



Unless melanism is a distinct disadvantage to this moth, there seems 

 to be no apparent reason why it should not have increased as much and 

 as rapidly as any of our melanic species, because I have proved, only this 

 season, that its hereditary tendency is stronger than in any other with 

 which I have experimented. At the end of June last year I was for- 

 tunate enough to get a pairing from fine examples of the variety, bred 

 from wild larv«, and from the eggs deposited, in June this year I reared 

 a considerable brood of the moth. Every specimen, without exception, 

 was of the extreme form of Varleyata. Now, even in its few known 

 localities (for it does not appear to occur at all in most places, even in the 

 districts which have produced it), the specimens reared by collectors only 

 average about three for every thousand larvae ; so it is highly improbable 

 that both parents of my last year's pair of moths were variety Varleyata — 

 possibly neither of them were ; yet not a single specimen from my brood 

 showed the slightest inclination to revert to the ordinary or any other 

 form than Varleyata. This has never occurred to me in any other 

 species. 



Of course melanism is not confined to Yorksliire and Lancashire. 

 There is plenty of it in Scotland, although generally, Scotch insects are 

 paler than the same species in Yorkshire. Rusina tenehrosa at Rannoch 

 is much darker and smaller than is the Yorkshire insect. Black Xylo' 

 •pkasia folyodon are more plentiful in Scotland than in Yorkshire. 

 Several species are melanic in the Shetland Isles which are normal in 

 Yorkshire — notably Noctua glareosa, which, almost black there, is pale 

 slaty grey or pale pink or rosy in Yorkshire. I have seen one Yorkshire 

 specimen, taken near Barnsley, of exactly the darkest Shetland form, .so 

 possibly the species here is in process of development towards melanism. 

 I can only say, however, that, with the exception of the specimen alluded 

 to, I can see no difference as yet in the species compared with what it was 

 thirty years ago. Melanic Dianthcecia conspersa are common in the 

 Shetland Isles, but quite normal in Yorkshire ; the species, however, 

 does not occur in the south-west of our county, and so not in the area 

 of melanism. In Delamere Forest, Cheshire, a black form of Aplecta 

 nebuJosa has been known as plentiful for some years, but although the 

 species has apparently been increasing in depth of colour for some time, 

 the extreme black Delamere form, variety Jiobsoni, was only noted here 

 for the first time last year, when a specimen was captured by Mr. Arthur 

 AVhitaker in Haw Park, Wakefield. Delamere Forest, too, produces a 

 very fine melanic form of Macaria litiirata, which as yet has not been 

 found at all in either Yorkshire or Lancashire, though the species occurs 

 right in the melanic area. Even the extreme south of England has ita 

 representatives of melanism. In a wood near Maidstone, Kent, Mr. 

 Goodwin takes a quite black form of Tephrosia consonaria, and in the 

 same wood almost black Boarmia consortaria, neither of which specie.5 

 are known to be melanic anywhere else. They do not, however, occur in 

 Yorkshire at all ; had they done so it is fair to assume they would 

 probably have become black long before they did so in Kent. The 

 genera Boarmia and Teiihrosia, indeed, seem particularly prone to 

 melanism, as, besides the species already alluded to, it occurs in Boarmia 

 rhomhoidaria, Boarmia abietaria, Boarmia roboraria, and I have seen it 

 in all the British species of Tephrosia except pnnctulata. London has ita 

 1906. X 



