48 



NOTES ON LEPIDOPTEROUS VARIATION IN THE 

 SKELMANTHORPE DISTRICT. 



B. MORLEY, 

 Skehiianthorpe. 



After some years of careful observation upon the variations 

 so striking^ly developed in many of our local species of lepi- 

 doptera, perhaps the following- brief account of a few instances 

 noticed may be of interest to others. It is not my intention to 

 try to explain any of the various causes that may have more or 

 less influence on the coloration of the species. My leisure being- 

 limited, it is impossible for me to carry out a large number of 

 experiments by breeding and crossing forms of extreme variety, 

 and recording the results thus obtained. Perhaps by such 

 means a few of the puzzling- phases of the variation might be 

 solved. At present it almost seems impossible to arrive at any 

 satisfactory conclusion as to what agent is, or agencies are, ir* 

 force causing the variations. The results, however, are such 

 that one need scarcely be surprised at any strange variation 

 that may develop. Not only is the melanic tendency remarkably 

 well developed in many species locally, but of recent years other 

 species not affected by melanism are actually showing a strong- 

 tendency to vary in the opposite direction, and frequently 

 examples are obtained, the bright colours of which are quite 

 surprising. It is not merely an instance of occasional bright 

 specimens, but a few species in particular seem to be g^radually 

 leaving their darker hues, consequently the predominating- 

 forms are much lighter than formerly. 



Cidaria stiffumata is a good example. Last spring I netted 

 a few, using no discrimination whatever, only for those in the 

 best condition. In due time, when pinned into the cabinet, the 

 difference in comparison with others taken on the same hedge- 

 row seven years ago was very striking indeed. The lighter 

 parts of the wings were more clear and the central band darker. 

 In the same locality a brighter form than this is frequently 

 taken, and very rarely the extreme form var. Pornttii (Robson) 

 is obtained also. It seems probable that the extreme forms 

 now so rare are in reality the forerunners of what the species 

 may ultimately become locally. The colour of this beautiful 

 variety is very striking, the central band and the blotch at the 

 base of the wings are quite black, as though all the colour in 

 the ruinaining parts of the wings has been assimilated into 



Naturalist, 



