Fertilisation of Orchids

MR. DARWIN, in his ``Fertilisation of Orchids,'' speaks of a Madagascar orchid (Angracum sesquipedale) with nectaries 11½ inches long, and supposes that these plants must be fertilised by the efforts of huge moths, with probosces capable of such expansion, to obtain the last drops of the nectar which is secreted in the lower part of these whip-like nectaries. Can any of your readers tell me whether moths of such a size are known to inhabit Madagascar? They would probably be Sphingidæ of some kind, as no other moths would combine sufficient size and length of proboscis.