395 



considered as one of our rarest as well as most beautiful butterflies j 

 and it is long since there has been any record of its occurrence in 

 England, with the exception of solitary individuals taken at distant 

 intervals. 



If this species comes over to us from the Continent, as some 

 think, it is a remarkable circumstance that nearly all the English 

 specimens " differ in colouring to a perceptible extent from the 

 Continental variety, the border being creamy-white instead of buff- 

 coloured." This, however, may perhaps be explained by the 

 circumstance of their being two broods on the Continent, at least 

 in Silesia, the spring brood " having the border of the wings sulphur 

 yellow, whilst the autumnal brood, like British specimens, have a 

 white margin." It is generally in autumn that the insect appears 

 in this country. If it is a genuine native, the question arises, and 

 it is one not easily answered, what are the peculiar conditions of 

 season or local influences to which we may attribute its very 

 irregular appearance 1 * 



It is more difficult to explain the appearance of insects, naturally 

 stationary, in places where they had not been seen before, es- 

 pecially if apterous, or which having wings very rarely use them. 

 This is a question which calls for close investigation on the part of 

 the local entomologist. 



It is also a curious fact, that while a large number of species 

 of insects, irrespective of the causes which first brought them into 

 a particular district, are found generally diffused through it, others 

 are so extremely local as to be confined to a very small space of 

 ground, perhaps to a single field, or to a particular hedge. Haworth, 

 the great Lepidopterist in the early part of this century, alludes to 

 this circumstance in his work, which being very scarce I give the 

 passage at length. He is speaking of the Fapilio cinada (the 

 Glanville fritillary butterfly), and he mentions it as one of those 

 insects — " So extremely attached to particular plants and to peculiar 

 situations and places, that a collector on one side of a hedge often 

 finds plenty, while another on the opposite side, the hedge alone 

 intervening, cannot procure a single specimen. They appear to 

 fly up and down, backward and forward, for a few score yards only ; 

 * See "Nature," vol. vi., p. 461 ; aud "Zoologist," vol. iii., p. 888. 



