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A Key to the superfamilies of the Lepidoptera
with special reference to North and South Dakota


About keys

Use of a key is the time honored method to identify an unknown organism when direct comparison with previously determined specimens is not possible.  Keys are more reliable than simple picture matching for the reason that in a comparison between your specimen (or photograph) and a textbook photograph, a suite of identification characters rather than overall similarity is emphasized.  Formerly, and ironically, the stumbling block to the use of keys by non-specialists has been mastering the terminology which in the past was clarified by the use of pen and ink illustrations.   Now, with the easy facility of digital imagery, terminology is clarified by the use of photographs.  Part of the digital imaging revolution that touches the realm of identification is that even an average digital picture may be easily enlarged or enhanced so that, given direction as to what to look for, 'key' characters can often be discerned.







Using a key is like playing a game of 'twenty questions' or reading a good detective story.  By answering crucial questions or analyzing critical clues, a conclusion is reached as to the identity of an object, a suspect, or in this case, the identification of a particular specimen to species.  Sets of questions employed in keys are termed couplets.   Keys on this web site are (as of this writing) of two types, either dichotomous couplets (two questions in apposition) or in the case of very large keys, quadrichchotomous sets of (4) questions, each question focusing on a particular character.  A short dichotomous key to identify a Cecropia moth, Hyalophora cecropia (the large moth on the homepage of this web site) might run as follows:
1.    Forewings and hindwings similar in shape and venation (primitive moths).
1.'   Forewings and hindwings of dissimilar shape and venation (most higher Lepidoptera. Go to 2


2.    Hindwings with scale fringe along outer margin at least 1/3 as wide as the wing (micro-moths)
2.'   Hindwings with fringe very narrow or absent (macro-lepidoptera)  Go to 3
3.    Wings coordinated by a frenulum-retinaculum coupling mechanism (most macro-moths).
3.'   Wings coordinated by an underlapping expanded humeral lobe of the hindwing (a few groups of macro-moths and butterflies)  Go to 4.
4.    Antennae capitate (clubbed) (butteflies).
4.'   Antennae not capitate (a few groups of macro- moths).  Go to 5.
5.    Forewing venation quadrifid (Lappet moths).
5.'   Forewing venation trifid (Mimallonids, Silk moths, Giant silk moths)  Go to 6.
6.    Antennae of males simple, cilliate, or bipectinate (Mimallonids, Silk moths Giant Silk moths subfamily Hemileucinae).
6.'   Antennae quadripectinate (Family of Giant silk moths, Saturniidae subfamilies Ceratocampinae, Saturniinae).  Go to 7.
7.    Antennae of males with apical 1/3 ciliate, of females ciliate (Royal moths, subfamily Ceratocampidae).
7.'   Antennae of both sexes quadripectinate (true giant silk moths, subfamily Saturniinae).  Go to 8.
8.    Discal cells of both wings closed (Early giant silk moths, tribe Saturniiini).
8.'   Discal cells of both wings opened (Derived giant silk moths, tribe Attaciini).  Go to 9.
9.    Dorsal abdomen with segmental spots or unicolored (genera: Samia, Rothschildia, Eupackardia and Callosamia),
9.'   Dorsal abdomen having each segment  with a pale posterior marginal band (Genus Hyalophora).  Go to 10.
10.  Wings with post median line white or black and white (H. columbia, H. euryalus, and H. gloveri).
10.' Wings with post median line black, white and red.  Hyalophora cecropia. Cecropia moth.


The above key was tailored specifically to unambiguously identify Hyalophora cecropia with the fewest number of couplets.  A somewhat longer key is required to key out far more species with the greatest efficiency.  Note that structural rather than color characters were used in all but the last two couplets and that even in this short key, specialized terminology was necessary.  In the Superfamily/family key that follows, images will clarify terminology.  





Last updated: 06/20/07

Dr. Gerald M. Fauske
collection manager, NDSIRC
research specialist, NDSU
216 Hultz Hall
Fargo, ND 58105
E-Mail: Gerald.Fauske@ndsu.nodak.edu

Published by the Department of Entomology 

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