Butterflies and Moths of North America

collecting and sharing data about Lepidoptera

Glossary of Entomological Terms

This glossary is not comprehensive. If you have a question about a term found on this site, please contact us so we can add a definition to the glossary.

am. line
The antemedial line, which separates the basal and median areas.


An extension of the antennal club in skippers (Family Hesperiidae).


A butterfly pupa.


The protective covering of silk that covers some moth pupae.


A butterfly that establishes a temporary or permanent population in a new area.


Active at dawn or dusk.


Active during daylight.


The back or posterior side.


A generation of adults. Many species are widely distributed across North America. In the north, these species may have only a single flight (one generation) each year, and the southern residents have two flights. When there is only one flight, adults emerge in spring or summer, mate, and deposit eggs. Depending upon the species, the caterpillars may complete their development in the fall, overwinter as pupae, and emerge in the following spring or summer. Alternatively, they may overwinter as caterpillars, resume development in early spring, then have a brief pupal stage and emerge as adults in spring or summer. In areas where there are two well-spaced flights annually, say April-May and July-August, it means that the adults that emerge in spring lay eggs that complete the entire life cycle by July-August, and that the July-August flight produces the overwintering generation.


The anterior wing, closer to the anterior (head) end of the adult.


The posterior (rear) wing.

larva (plural: larvae)

The caterpillar; the long, worm-like stage of the butterfly or moth. It often has an interesting pattern of stripes or patches, and it may have spine-like hairs. It is the feeding and growth stage. As it grows, it sheds its skin four or more times so as to enclose its rapidly growing body.

Derived from the Latin lepido= scale + ptera= wing, and it is the Order that contains all butterflies and moths.

life history

The taxonomic, biological and ecological studies of a species.

NatureServe Global Status

NatureServe is a non-profit conservation organization.
Global ranks indicate the rarity of a species at a global scale. Species may be fairly common globally but imperiled locally. Global ranks have the following meaning:
G1 - Critically Imperiled - At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors. G2 - Imperiled - At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors. G3 - Vulnerable - At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors. G4 - Apparently Secure - Uncommon but not rare; some cause for long-term concern due to declines or other factors. G5 - Secure - Common; widespread and abundant.

* ? or Q = status unknown or uncertain


Active at night.


To lie dormant.


A mate-locating behavior of butterflies characterized by males flying through likely habitat in search of receptive females.


A mate-locating behavior of butterflies characterized by males sitting on objects or spaces by which receptive females are likely to pass.

pm. line
The postmedial line, which separates the median area from the subterminal area in the typical noctuid pattern.


The coiled tube through which adult butterflies and moths imbibe nectar and other fluids.


The transformation stage within which the caterpillar tissues are broken down and the adult insect's structures are formed. The pupa of most species is brown or green and blends into the background. Many species overwinter in this stage. In butterflies, the pupa is called a chrysalis. A moth pupa is sometimes a cocoon.


Not truly entomological terms, but the status is used by this system's regional coordinators to describe why and how a species is found in a particular location.

  • Resident: species predictably resides in & reproduces in the location of this record
  • Nonresident: species has been introduced or generally does not naturally occur in the location of this record
  • Stray: species occasionally strays to this location, outside of resident locations, but is not found here every year
  • Temporary Colonist: species does not survive winters or other seasons in this location, but does immigrate & reproduce in the locality
  • Migrant: species has periodic or regular migrations and can be found in this location during migrations
  • Unknown: coordinator cannot determine status of this species in this location

taxonomic group

A group of related organisms; a category in taxonomy.


The science of classifying living organisms.


The small appendages attached to the protothorax just above and in front of the forewing base, curling over the costa and covering the base. Singluar: tegula.


Tubular branching rods that extend from the bases to the margins of the wings and provide support for the wing membrane.


Pattern of formation and branching of veins in wings.


The front or anterior side; the belly.

voucher specimen

A specimen archived in a permanent collection (usually in a museum, an institution with a mandate to preserve materials indefinitely).

wing span

Distance between the tips of the forewings; measured in centimeters (cm) or inches (in).