LEPIDOPTERA-RHOPALOCERA IN MAURITIUS. 133 



work Langdale Pikes and other mountains for E. epiphron, 

 and Lingmoor was of very easy access for collecting over the 

 heather. 



(To be continued). 



NOTES ON THE INCREASE IN NUMBERS OF LEPIDO- 

 PTERA-RHOPALOCERA IN MAURITIUS. 



By Captain B. Tulloch, F.E.S. 



In England one has to deplore the fact that not only are local 

 species of butterflies becoming still more local, and in some cases 

 almost extinct, but also that many of the commoner species are 

 gradually becoming scarce. This, of course, is due to many 

 causes — as, for instance, the disappearance of forest lands, the 

 drainage of fens, the trimming of hedges, and also to the in- 

 satiable desire of many "collectors" to obtain a long series of 

 the same species. This desire for a series always seems to me 

 to be one of the chief reasons why so many species of butterflies 

 and moths are rapidly disappearing in Britain. In Mauritius, 

 however, the very opposite is occurring, for not only are new 

 species arriving by some means in the island, but even those 

 species which do find a footing increase rapidly in numbers. 

 Why this increase in numbers of a particular species should 

 occur I will endeavour to show later on. 



In 1833 Boisduval enumerated twenty species of butterflies as 

 inhabiting Mauritius, or, including one doubtful species, twenty- 

 one in all. Roland Trimen visited the island in 1865, and dis- 

 covered twenty-six species. I myself arrived at the island in 

 March, 1899, and soon found three other species, all common, 

 .not noticed by Trimen, viz. Papilio demoleus, Zizera knysna, and 

 Z. gaika. 



I have just received a letter from Lieut. -Colonel N. Manders, 

 R.A.M.C., who asks me whether I found Cocynis Ugneus, Zizera 

 maha, and a species of Lyccena not previously mentioned. He 

 stated that these three were all common in parts of the island. 

 As I worked Mauritius pretty thoroughly whilst I was in the 

 island, and did not find the three species mentioned, I conclude 

 that they are also of recent introduction. But the most extra- 

 ordinary thing is the rapidity with which a species multiplies 

 once it has been introduced into the island. Papilio demoleus 

 did not exist in Mauritius in 1865, yet whilst I was there it was 

 to be found everywhere. 



In the library at Port Louis I found a French natural history 

 of Mauritius, in which mention is made of a white butterfly 

 having been seen in the island, and the author, writing some- 

 where about the beginning of the nineteenth century, wonders 



