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Terms Used in the Classification of Lepidoptera

Arthropoda: The name of the phylum that includes all of the insects. This phylum is characterized by its members having jointed appendages, an exoskeleton, and a series of segments along the body axis, easily seen on the outside surface but not divided internally. This phylum has more identified species within it than any other phylum on Earth.

Binomial Nomenclature: Also sometimes called “scientific naming.” This is the method of unambiguously identifying any species by assigning a pair of words to it—the genus name followed by the species name. Thus, Homo sapiens is the universally accepted name for humans. A goal of lepidopteran taxonomic study is to provide such a pair of names for every known species within the order Lepidoptera. The genus-species designation always reflects current understanding of the relationship of a species with others; thus, the name must be changed if new knowledge alters our understanding.

Butterflies: See the FAQ on comparing butterflies with moths..

Class: The taxonomic category higher (more inclusive) than order and lower (less inclusive) than Phylum. Thus, butterflies and moths are in Class Insecta, which is part of Phylum Arthropoda.

Ditrysia: The name for one of the two suborders of Order Lepidoptera (the other one is Monotrysia). Encompassing most families of moths and butterflies, this group is distinguished by having separate openings at the tip of the female’s abdomen: one for mating and the other for egg laying. Contrast this with the female abdomen of the Monotrysian families, where there is a single opening for these two functions.

Domain: The largest taxonomic category. Two or more kingdoms that share some features comprise a domain. Animals (in kingdom Animalia) are in domain Eukarya.

Family: The taxonomic category lower (less inclusive) than order and higher (more inclusive) than genus. All of the members of a family should possess shared anatomical, biochemical, and embryological features. Order Lepidoptera includes over 75 families (the exact number is unkown: our imperfect knowledge leads to disagreement among experts on this fundamental issue).

Form: A distinguishable variant within a population. For instance, in some species there are differently colored forms of the adult butterfly or moth at different times of the year: a spring form and an autumn form.

Genus: The taxonomic category higher (more inclusive) than species and lower (less inclusive) than family. All of the members of a genus should possess shared anatomical, biochemical, and embryological features. Plural of genus = genera.

Lepidoptera: The name of the order of insects that includes the butterflies, skippers, and moths. The feature that distinguishes Lepidoptera from other insects is the possession of tiny overlapping scales on the wings of the adult. Other features of Lepidopteran adults include: four membranous wings, forewing and hindwing on each side of the body coupled at their base, and mouthparts (if present and functional) shaped into a sucking tube a proboscis). Features of larvae (caterpillars) include possession of chewing mandibles, stubby prolegs on the abdomen, and silk-producing glands.

Macrolepidoptera: An “unofficial” term referring to the Lepidopteran families whose adult members tend to be rather large. An incomplete list of macrolepidoptera would include all of the butterflies and skippers and such moths as the Geometridae, Arctiidae, and Noctuidae. It should be emphasized that some “macros” are smaller than some microlepidoptera, and vice-versa.

Microlepidoptera: An “unofficial” term referring to the Lepidopteran families whose adult members tend to be rather small. All microlepidoptera are moths. A few families whose members would typically be called microlepidoptera include the Gelecheidae, Tortricidae, and Pyralidae. It should be emphasized that some “micros” are larger than some macrolepidoptera, and vice-versa.

Monotrysia: The name for one of the two suborders of Order Lepidoptera (the other one is Ditrysia). Encompassing relatively few families of moths, this group is distinguished by having a single opening at the tip of the female’s abdomen, used for both mating and egg laying. Contrast with the female abdomen of the Ditrysian families, where there are separate openings for these two functions.

Moths: See the FAQ on comparing moths with butterflies.

Order: The taxonomic category higher (more inclusive) than family and lower (less inclusive) than Class. Thus, butterflies and moths are in Order Lepidoptera along with all of the other insects of Class Insecta.

Phylum: The taxonomic category higher (more inclusive) than class. Butterflies and moths are in phylum Arthropoda.

Skippers: See the FAQ on this.

Species: Perhaps the most controversial term in the classification of organisms. There are currently at least a dozen somewhat different ways of defining the concept of species, each with its own vociferous proponents. All would agree that it is the taxonomic category less inclusive than that of genus. Most people adhere to the idea that fertile female members of a species must be capable of successfully reproducing with fertile male members. According to this definition, if successful reproduction cannot be consistently achieved between two populations, then those populations represent different species. Another way to distinguish different species (and the way that is the most practical in the “real world” is to look for consistent significant differences in larval, pupal, and adult anatomy. (“Anatomy” might include molecular anatomy—the composition of the molecules within the organism.) These definitions rely somewhat upon human opinion and therefore lead to disagreements about whether two closely related groups (typically in the same genus) are representatives of a single species.

Suborder: A taxonomic category that divides an order into two or more groups. See Ditrysia and Monotrysia.

Subspecies: A taxonomic category below the level of species. The organisms that comprise a species can sometimes be distinguished from each other to the extent that they can be placed into two or more subspecies. Usually, subspecies distinctions are made on the basis of small anatomical differences between populations residing in different geographical areas. Some biologists reject the concept of subspecies, saying that such subdividing is too artificial and the differences are too impermanent to be of significance. The term “race” is usually considered to be synonymous to “subspecies.”

Systematics: The area of biological study that seeks to understand the taxonomy of organisms within the larger area of evolutionary biology. That is, systematists study both the relatedness of organisms and the evolutionary mechanisms by which organismal diversity has come into being.

Taxonomy: The area of biological study whose tasks include the proper naming (from domain all the way down to species and even subspecies) of the organisms that exist or have existed on Earth. Taxonomists strive to provide unambiguous names that give accurate information on the degree of similarity among organisms. Taxonomic tools include anatomical examination, study of behavior, molecular techniques, and statistical analysis. Taxonomy is a discipline within the science of systematics.