I searched again through VN's ADA and selected a few examples of the "mix" :
1.‘My love,’ said Van, ‘my phantom orchid, my lovely bladder-senna! .’
2. "My magic carpet no longer skims over crown canopies and gaping nestlings, and her rarest orchids. Insert."
3. " ‘Well,’ said Van, ‘you can always make a little cream, KREM or KREME — or even better — there’s KREMLI, which means Yukon prisons. Go through her ORHIDEYA.’//‘Through her silly orchid,’ said Lucette."
4. "Patient Ada wanted her to copy not mechanically... Casually, lightly, she went on to explain how the organs of orchids work — but all Lucette wanted to know, after her whimsical fashion, was: could a boy bee impregnate a girl flower through something...?"
5. "never to be confused with testiculus, orchid..."
6. "...a Lurid Oncidium Orchid in an amethystine vaselet."
7." ‘She’s terribly nervous, the poor kid,’ remarked Ada stretching across Van... Oh, what a good sight! Orchids. I’ve never seen a man make such a speedy recovery.’
8. DB: "p.321. Knabenkräuter: Germ., orchids (and testicles)".
9. 'Dr Krolik ...kindly gave me five young larvae of ... Carmen Tortoiseshell. ...(At ten or earlier the child had read - as Van had - Les Malheurs de Swann, as the next sample reveals):"
10." 'I think Marina would stop scolding me for my hobby ("There's something indecent about a little girl's keeping such revolting pets...," [ ] if I could persuade her to overcome her old-fashioned squeamishness and place simultaneously on palm and pulse (the hand alone would not be roomy enough!) the noble larva of the Cattleya Hawkmoth (mauve shades of Monsieur Proust), a seven-inch-long colossus flesh colored, with turquoise arabesques, rearing its hyacinth head in a stiff "Sphinxian" attitude.' ...(Lovely stuff! said Van, but even I did not quite assimilate it, when I was young. So let us not bore the boor who flips through a book and thinks: 'what a hoaxer, that old V.V.!')"

** - I was quite familiar with Brian Boyd's references to the Cattleya orchid. From his annotations to 56.06-10: 'the noble larva of the Cattleya Hawkmoth (mauve shades of Monsieur Proust), a seven-inch long colossus, flesh colored, with turquoise arabesques, rearing its hyacinth head in a stiff “Sphinxian” attitude': “Let me also evoke the hawkmoths, the jets of my boyhood!” Nabokov recalls with great fondness in SM (134). Hawkmoths, of the family Sphingidae, are usually largish moths, which, because they hover over the flowers they feed on at dusk, are often confused with hummingbirds. “Sphinx” is “the typical genus of hawkmoths, originally coextensive with the family Sphingidae, but now including only a very small part. The larva often assumes a position suggestive of the Egyptian sphinx.” (W2) [ ] "The Cattleya Hawkmoth, called at 56.32 “the Odettian Sphinx,” is an invented hawkmoth Nabokov labels in A1 “Sphinx odetta.” Like many hawkmoths it is presumably named after its foodplant, in this case the Cattleya orchid, any orchid of the genus Cattleya, whose flowers are among the most gorgeous known. In Un Amour de Swann, Swann’s first physical advances towards Odette start when a jolt in their carriage leads to his straightening the cattleyas in her corsage. [ ]Nabokov suggested to Penguin that the cover of its edition of Ada should be a Cattleya orchid, and he drew one for the publisher that was in fact closely followed for the 1970 and 1971 editions. / The comically overt sexual double-entendre in describing the caterpillar is a tribute to the “mauve shades of Monsieur Proust,” for the mauve-pink lip of Cattleya bicolor, with its deep mesial groove, looks strikingly like the labia of the human female. The “seven-inch colossus” anticipates Van’s misunderstanding in a noisy restaurant when he supposes Lucette’s “it looked to me at least eight inches long--” refers not as she intends to his duelling scar but to something else, and he modestly murmurs in reply “Seven and a half.” (411.25-27) The innuendo recalls a passage from the normally chaste The Gift, where Fyodor anticipates the “beginning (tomorrow night!) of his full life with Zina--the release, the slaking--and meanwhile a sun-charged cloud, filling up, growing, with swollen, turquoise veins, with a fiery itch in its thunder-root, rose in all its turgid, unwieldy magnificence.” (357) Cf. also with “mauve shades of Monsieur Proust” 9.18-29: “ ‘dark blue’ . . . . Proust . . . favorite purple passage . . . his adjacent ultramarine.” “Hyacinth”is a light to moderate purple. In his lectures on Proust Nabokov points out the “mauve color, the violet tint that runs through the whole book, the very color of time. This rose-purple mauive, a pinkish lilac, a violet flush, is linked in European literature with certain sophistications of the artistic temperament. It is the color of an orchid, Cattleya labiata (the genus called thus after William Catley, a solemn British botanist)./ (LL 241) Cf. also the “Forbidden Masterpiece” painting into which Van feels himself transferred when sunbathing with Ada by the Cascade: 141.13-14: “There was a crescent eaten out of a vine leaf by a sphingid larva.” MOTIF: flowers; orchids."