VARIETIES. 



V2S 



genus Agrotis, which Mr. Haworth describes, and which have 

 now been satisfactorily reunited, but would only refer to one 

 or two recent instances. Polia CM is stated to be almost 

 peculiar to the more northern parts of this island ; and, I 

 presume, most of the specimens found in the London cabinets 

 have been collected in Derbyshire and Yorkshire. The great 

 uniformity in the general colouring of these specimens would 

 almost induce one to suppose they had been taken by only a 

 few collectors. It was not therefore much to be wondered at, 

 that Mr. Curtis should have pronounced one of the dark 

 varieties a new species, nor that Mr. Stephens, liaving never 

 seen the collecting links, should subsequently have described 

 a similar variety received from Edinburgh, under the name of 

 P. olivacea. Near Newcastle the insect is rather common, 

 and occurs of every shade, from the hoary tinge of what is 

 described as the typical variety in Mr. Stephens' Illustrations, 

 or even from an almost pure white, to the olive-green of his 

 P. olivacea. The diversity of cplouring in an extensive series 

 is really beautiful ; for, besides meeting with specimens of both 

 sexes, having all the wings dark-coloured, or dark anterior 

 and light posterior, and vice-versa, or all light coloured, some 

 are scattered over with fulvous spots, like P. clysodea, whilst, 

 in others, the strong black markings form a striking contrast 

 with the hoary tints of the wing. In fact, scarcely two spe- 

 cimens are precisely similar. It has generally been supposed 

 that the larva of this moth feeds on the Sonchi, Lactucce, 

 &c. : — but I am inclined to believe that its food is lichens. 

 My reason is, that the perfect insect, when discovered in 

 repose,^ is always to be met with on walls overgrown with 

 lichens ; and every entomologist knows that moths in ge- 

 neral, with the exception of the species whose larvae feed on 

 the Crypiogamia encrusting stones, or at least are presumed 

 to do so as the BrynphUce, Aids muraria, Aploccra ccssiata, 

 Sec, dislike roosting on stones. Besides, I have taken speci- 

 mens in such situations so very recent, that they could not 

 have quitted the pupa state more than a few minutes pre- 

 viously. I regret that my attempts to rear the insect from the 

 egg, or to discover the larvae, have hitherto been unsuccessful. 



* I never knew of more than a single example being taken on tlie vi'iug, anil 

 that was in the immediate vicinity of the park-wall at Meldon, wliich is a very 

 ancient one. 



