There are four sections to this Guide. Sections 1 and 2 make up the catalogue proper. Section 2A is the principal one. Here, all the butterflies and moths mentioned in Nabokov's published writings are listed in alphabetical order and annotated wherever necessary. All lepidoptera are listed under the scientific name valid around the year 2000. Whenever Nabokov used some other name (a scientific name that has become obsolete, a fragmentary, common or idiosyncratic one), these too are listed alphabetically, with two small arrows ("»") pointing to the current scientific name where further information will be found. Section 2B lists Nabokov's Lepidoptera by work and page number and points to the appropriate catalogue entries.
Considerable effort has been made to ascertain what actually are the currently valid scientific names. For the European moth fauna, the Guide relies largely on the checklists by Karsholt & Razowski and Leraut. For European butterflies, the most recent source was the French translation of the Collins Field Guide published in 1999. Disconcertingly, it disagrees with the Collins Field Guide and with the checklists by Karsholt & Rasowski and Leraut about dozens of generic names, even though the same authors were involved and the books were only two years apart. Some species have reverted to their older names, while a number of new generic names have appeared; others have changed genera. The authors, however, assured the user that this was the state of the art and that they had taken into account the classification by Minet (1986), Karsholt & Rasowski (1996) and Leraut (1997). The fritillaries (that is, the genera Argynnis, Boloria, Brenthis, Clossiana, Fabriciana, Speyeria, etc.), formerly considered to be a subfamily of nymphalids (Argynninae), have been made a tribe of Heliconiinae (longwings), Argynnini. For the blues of the Polyommatus and Nabokovia Sections, the Guide strictly follows the classification by Bálint & Johnson (1997). The main sources for the North American butterfly fauna have been the checklists by Miller & Brown and by Hodges e.a. as well as the Audubon Guide. For other faunas and for moths, things are less clear, and the names used may sometimes not reflect the state of the art. There will be recent name changes I have overlooked, and as names are a highly contentious matter, there will be scientists who do not agree with the name changes I have acknowledged. In no case, of course, is a name used to be taken as a taxonomic statement.
A catalogue entry in Section 2.1 will typically look like this:
*Biston (ex Amphidasis) betularius Linnaeus, 1758 [Geometridae, Ennominae]: This probably is the moth referred to… *Gift 24
& Ac: Bíston/Amphídasis betulárius ● En: Peppered Moth, Pepper-and-Salt Geometer ● Fr: la phalène du bouleau, le géomètre du bouleau ● Ge: Birkenspanner ● It: geòmetra della betulla ● Ru: пяденица березовая ● Sp: bistón del abedul
* : an asterisk preceding the item means identification by conjecture (the name itself is not mentioned by Nabokov). Asterisks preceding a common name: this is not a recognized name, but plausible.
Biston betularius: the currently valid scientific name.
(ex Amphidasis): 'synonym'. This moth was formerly ranged with the genus Amphidasis. If names or spellings of the same taxon have become obsolete (as junior synonyms or homonyms or for some other reason), they are all treated as 'syn' here. Where it is known from the checklists that the reason was homonymy, the 'syn' turns to 'hom'. It would be futile to even try to list all the 'syn' that exist, and all the spurious synonyms caused by the spelling errors the literature is teeming with. Only those Nabokov himself used or quoted and some encountered in fairly recent handbooks are included, simply as a cue as to what alternative names one might want to look up in handbooks of different times and different languages. However, not all synonyms only passingly mentioned in Nabokov's technical papers are listed.
Linnaeus: the name of the taxon's author.
1758: the year the original description (OD) was published. In the scientific literature, author and year usually appear in parenthesis. This practice is not observed in this Guide which needs parentheses and brackets for other purposes.
[Geometridae, Ennominae]: the name of the family and/or subfamily to which Biston betularius belongs.
This probably is the moth referred to…: explanatory notes or comments.
*Gift 24: the insect is mentioned on page 24 of the novel The Gift. The page numbers refer to the Vintage paperback edition, wherever available; if not, to the original hardcover edition. For the stories, the page numbers refer to The Stories of Vladimir Nabokov (New York, Knopf, 1995). Lep1 through Lep23 are Nabokov's lepidopterological papers, reviews and notes, listed and summarized in Section 4A. Int1 etc. are uncollected interviews with mention of Lepidoptera, as listed in Section 4B. Most of the titles are abbreviated in a way that should be obvious (→Abbreviations). For the Nabokov-Wilson Letters, letter numbers are given instead of page numbers, to take into account that the numbering has changed with the expanded editions of 1995 (in German) and 2001 (in English); the old letter numbers are added for convenience.
& Linguistic information: Ac: accented syllables (only where necessary and ascertainable) ◦ En: English common name ◦ Am: American ◦ Fr: French ◦ Ge: German ◦ It: Italian ◦ Ru: Russian ◦ Sp: Spanish
As to the capitalization of common names, there is no consistency, neither in the general literature nor in Nabokov's writings. Side by side one finds 'Brimstone' and 'brimstone,' 'Fritillary' and 'fritillary,' 'Pierids' and 'pierids,' 'Polyommatine' and 'polyommatine,' sometimes in one and the same source. (There is exactly the same problem in French.) For the better or the worse, in this Guide a modest attempt at consistency has been made.
In agreement with prevailing practice, the common names of individual species and subspecies are treated as proper nouns and always capitalized (eg 'Atlantic Fritillary,' 'Karner Blue,' 'White-lined Sphinx'). In agreement with Webster III, nouns or adjectives derived from New Latin names above the generic level are not capitalized (e.g. 'Lycaenidae,' but 'lycaenids'; 'Polyommatini,' but 'polyommatine').
The chief problem arises with group names. Is it to be 'Hairstreak' or 'hairstreak'? Are they individualizing proper nouns or generalizing appellations? Obviously they are something in between. Many authors have opted for capitals, and in some cases these do facilitate reading. However, as all major dictionaries concur in putting them in lowercase, they are not capitalized except where they are part of a species name (e.g. 'admiral,' 'alpine,' 'anglewing,' 'apollo,' blue,' 'brown,' 'copper,' 'fritillary,' 'grayling,' 'hairstreak,' 'heath,' 'ringlet,' 'swallowtail,' 'tortoiseshell,' 'white,' 'wood-satyr').
The American common names for Lycaenidae (gossamer wings) and Nymphalidae (brushfoots) are not employed; they are called lycaenids and nymphalids, respectively.
 Ole Karsholt & Józef Razowski, The Lepidoptera of Europe: A Distributional Checklist, Stenstrup, Denmark (Apollo) 1996
 Patrice J.A. Leraut, Liste systématique et synonymique des lépidoptères de France, Belgique et Corse, Paris (Alexanor) 21997
 Tom Tolman & Richard Lewington, Guide des Papillons d'Europe et d'Afrique du Nord, traduction et adaptation: Patrice Leraut, Lausanne (Delachaux et Niestlé) 1999.– Tom Tolman & Richard Lewington, Collins Field Guide to Butterflies of Britain & Europe, London (HarperCollins) 1997
 Joël Minet, "Ébauche d'une classification moderne de l'ordre des lépidoptères," Alexanor (Paris), 14 (7), 1986, p. 291–313
 Cf. R. De Jong / R.I. Vane-Wright / P.R. Ackery, "The higher classification of butterflies (Lepidoptera): problems and prospects," Entomologica scandinavica (Copenhagen), 27, 1996, p. 65–101
 Lee D. Miller / F. Martin Brown, A Catalogue/Checklist of the Butterflies North of Mexico, Memoir No. 2, Sarasota FL (The Lepidopterist's Society) 1981
 Ronald W. Hodges / Tatiana Dominick / Donald R. Davis / Douglas C. Ferguson / John G. Franclemont / Eugene G. Munroe / Jerry A. Powell (eds.), Check List of the Lepidoptera of America North of Mexico, London (Classey) 1983
 Robert Michael Pyle, The Audubon Society Field Guide to North American Butterflies, New York (Knopf) 1981 ff.