Vanessa Atalanta by Gene Barabtarlo, The Nabokovian 13 (Fall 1984), 27-28.
In his notes to line 347 of Shade's Pale Fire Prof. Kinbote quotes "the jumble of broken words and meaningless syllables" which is supposed to encode a message from Aunt Maud's spirit (in the "Old Barn" episode). The transcription goes
pada ata lane pad not ogo old wart alan ther tale feur far rant lant tal told
Kinbote then makes a half-hearted attempt to unscramble the string: "some of the balderdash may be recombined into other lexical units making no better sense (e.g., 'war', 'talant', 'her', 'arrant', etc.)". The gloss is not totally disorienting; in fact, "talant" may be a clue but in an oblique application.
I propose that the message contains the thrice repeated and scattered Latin name of the Red Admirable butterfly, Vanessa atalanta:
pads АТА LANe pad noT ogo old wArT ALAN Ther tAle feur far rAnT LANT tAl told
This may be indeed a warning issued to John Shade by his Aunt's ghost; the beautiful Nymphalid hovers around him just six lines before his death. The Red Admirable Theme is quite important in the novel. The Kinbotian Index lists it as being "evoked, 270; flying over a parapet on a Swiss, hillside, 408; figured, 470; caricatured, 949; accompanying S's last steps in the evening sunshine, 993." The fatidic role ascribed to this butterfly is discussed by Nabokov in his interview with Alfred Appel (Strong Opinions, 170).
With the kind permission of Mrs. Vladimir Nabokov, I should like to quote here a passage in her letter to me on the subject, which definitively decodes the cipher (she refers to her Russian rendition of it; interpolations in square brackets mine):
The entire message of the ghost, if carefully read, represents a clear warning from Aunt Maud advising Shade not to go to Goldsworth's. Pada and tata hint at "father"; then: "pada ATA i ne LANTA. Then: "nedi" — neydi, ne khodi [NOT oGO]. Then: oGOL VARTA [Go OLD WART]. Strakh (feur), lane [...], and tale are also represented [in the Russian version]".