62 LEPIUOPTEROUS FAUNA OP PORTLAND. 



One of the most curious facts in connection with this genus is 

 that another species, Nepticula centifoliella, exists, whose larva is 

 indistinguishable from that of N. anomalella; the larva makes a very 

 similar mine in a rose leaf and spins a similar brown cocoon. But 

 when the perfect insect emerges it is strikingly different, as the 

 fore- wing is crossed near the middle by a bright silvery bar and there 

 are also other smaller differences. This latter species has been found 

 at one or two places in England, but not in any numbers, and 

 always, I believe, in company with N. anomalella, so that one may 

 collect a great many larvae of the two species, and breed one or two 

 N. centifoliella and dozens of N. anomalella. It is generally 

 considered one of the rarest of the genus Neptwda. 



I have been much surprised, therefore, to find that at Portland 

 one gets on the rose bushes in the locality where it occurs nothing 

 but the usually rare species N. centifoliella, whereas as far as I 

 have seen N. anomalella is entirely absent from the island. It is 

 not improbable, however, that it may occur in gardens on rose trees 

 which have been brought from other parts of the country, as it is 

 generally common on garden roses. N. centifoliella has not been 

 found elsewhere in this county, though N. anomalella is abundant. 



I have no distinct theory to offer on this point, but it certainly 

 shews, in conjunction with other facts, that something very 

 peculiar influences the insect fauna of Portland. N. centifoliella 

 is figured on the moth plate in the last volume of our " Proceedings." 



With this very remarkable case of these two moths, which 

 belong to the smallest known group, and of which one wing only 

 measures a tenth of an inch in length, and sometimes less, I will 

 close my list of the chief peculiarities in the moths of Portland. 

 There are many others of a similar nature, but, perhaps, not quite 

 so marked, which might be mentioned; but enough have been 

 brought forward to lead us to the conviction either that Portland 

 and the mainland have had no communication with each other for 

 a very long period, or that there is something very unusual in the 

 climate or general conditions of life on Portland which enables 

 moths which can exist either not at all or only with difficulty in 



