Butterfly Glossary

Abdomen: One of the three main regions comprising an insect. It is the region in the rear.

Biennial: Requiring two years to complete development and life cycle.

Bract: A specialized plant leaf which is most commonly located directly beneath a flower.

Brood: A single generation of butterflies, all of which fly during the same time period.

Chaparral: A type of dry habitat consisting of short shrubs and scrubby oaks.

Chevron: A shape of a mark, much like ">", found on some caterpillars and butterflies. 

Chrysalis: The smooth outer covering of a butterfly pupa.  Often, the term "chrysalis" is used to refer to the pupa itself.[image]

Cocoon: A silken sturcture that encloses the pupa of some butterflies and skippers.  Most butterfly pupae are naked, and what you see is really their skin!

Costal fold: The fold along the leading edge of the forewing of a butterfly.  It often contains scent scales used to attract other butterflies.

Cremaster: A structure, much like a hook, on the rear of a chyrsalis, which helps to secure the chrysalis to a leaf, twig, etc.

Diapause: A state of halted development.  Insects typically overwinter in this state, waiting until spring to continue growing and molting or to finish pupating.

Dorsal nectary organ: An organ located on the rear of some caterpillars which emits a sugary solution consumed by ants. The ants feed on the solution and in turn protect the caterpillar from predators.  It is also called a honey gland.

Estivation: A state of dormancy, without movement or development, entered into by an insect to survive a hot or dry period. Also may be spelled as "aestivation."

Everscible tubercle: A kind of tentacle housed within the body of some caterpillars, at the rear.  If the caterpillar feels threatened by a potential predator, it can be pushed out to release a chemical, which mimics an ant alarm pheromone. This scent causes the ants to become aggressive and the potential predator either leaves or the ants attack it.

Eyespot: A mark found on some caterpillars and butterflies.  It is round and has a spot in the center (the "pupil") of a different color.[image]

Filament: A long (occasionally short), thin, fleshy extension, usually paired, extending off the back and sides (less commonly the abdomen) of a caterpillar.

Flight: The period of time during which butterflies from the same generation fly.  It can also be used to refer to a single generation of butterflies. In the species accounts presented here, the period of time given for when adults "fly" (for example, from May to early August) is the length of time adults may be observed.  Those adults may be from one generation or from several successive generations.

Genus (pl. Genera): A group of related species.  The genus name is the first word in the scientific name of a species.  For example, the monarch's scientific name is Danaus plexippus.  Danaus is the name of the genus the monarch belongs to.

Hair: One of the structures typically found on a caterpillar.  It can come in a variety of forms, such as feathery, branched, or forked.  The more correct term for this kind of hair is seta (pl. setae).

Hair pencil: A hair-like structure on the legs or abdomens of some butterflies and moths that is believed to aid in the distribution of pheromones during courtship.

Head: One of the three main regions comprising an insect.  It is the region at the front and bears most of the sensory organs, such as the antennae.

Hibernaculum: A structure made by some caterpillars in which they overwinter.  Often it consists of a leaf rolled and tied with silk.

Hibernation: A state of dormancy or reduced activity typically entered at the onset of winter.  Hibernating saves the animal a great deal of energy at a time where food is not readily available.  Also referred to as "overwintering."

Hill topping: A behavior commonly exhibited by Swallowtail (Papilio spp.) butterflies where males and females will congregate at a high point in the landscape, such as at the top of a ridge.  By doing so, each individual butterfly's chance of finding a mate is increased.

Holarctic: Occurring in the temperate regions of the entire Northern Hemisphere.

Honey gland: See Dorsal nectary organ.

Honeydew: A sugary solution secreted by aphids, some caterpillars, and other insects, which is agreeable to some insects, and is consumed.

Horn: A hardened structure that extends from the head of some caterpillars.

Host plant: The plant used for food by a specific species.  Butterflies typically lay their eggs on the host plant used by the caterpillar.  A single species of butterfly may use one or several species of plants as host plants.

Hybridize: To breed with a member of a different species.  Often the offspring of such a union, called a hybrid, is infertile.

Instar: Individual growth stage of a caterpillar.  Instars are separated by molts.

Introduce: To bring a species, either inadvertantly or intentionally, from another area into a new area where it has not existed previously.  Introduced species are the opposite of native species.

Legume: A specific type of plant, belonging to the family Fabaceae (formerly Leguminosae).  These plants produce their fruit as a pod and generally possess nitrogen-fixing bacteria in nodules on their roots.   Examples of legumes include peas, beans, and alfalfa.

Migrate: To travel at regular intervals in large numbers in a particular direction, typically north or south.

Molt: The shedding of the exoskeleton ("skin") of a caterpillar allowing for growth. Caterpillars experience several molts before pupating.

Morph: A distinct, readily observeable type of a given species.  For example, within the species Colias occidentalis, there are both yellow and orange morphs.

Nest: A structure made by some caterpillars, typically from leaves tied together with silk. The caterpillars live and feed within the nest together.

Osmeterium: A Y-shaped gland located behind the head of some caterpillars which can be pushed out to emit a chemical disagreeable to potential predators.

Oviposit: To lay eggs.  The process of laying eggs is called oviposition.

Parasitic: To obtain nutrients necessary for life from another living organism. For example, a mosquito is a parasite of warm-blooded animals, including humans.

Palpus (pl. Palpi): One of a pair of appendages on the front of a butterfly's head which protect the feeding apparatus, the proboscis.

Patrol: A strategy of mate location used by male butterflies, consisting of constant flight.

Perch: A strategy of mate location used by male butterflies, consisting of waiting in a constant location for females to pass by.

Petiole: The stalk of a leaf, attaching it to the stem.

Pheromone: A scent chemical used for communication. For example, male butterflies emit pheromones to attract female butterflies of the same species.  Some caterpillars can emit a chemical which mimics an ant alarm pheromone.

Proboscis: A biological term typically used to describe a long, flexible feeding structure.  In butterflies, it is the long, coiled tube through which they feed.

Proleg: A "false" leg, used in locomotion, found on the abdominal segment of a caterpillar.  A caterpillar has five pairs of prolegs. Caterpillars, like other insects, have only six true legs, and these arise from the thorax (or thoracic segments).

Pubescence: Soft, fine hair or hair-like structures.

Puddling: A behavior of some butterflies in which they congregate at puddles, moist soil, or dung to obtain moisture and salts.[image]

Pupa (pl. Pupae): The resting stage between juvenile and adult forms of an insect; in butterflies, the pupa is encased by a chrysalis.  Typically this stage (the pupal stage) is immobile and does not feed; internally, however, complete reconstruction is taking place.[image]

Pupate: To become a pupa.

Riparian: Alongside a stream, river, or other body of water.

Sagebrush steppe: A type of dry habitat characterized by sagebrush and other shrubs and short grasses.

Scent scales: Specialized scales on the wings of some butterflies, typically males, which produce pheromones.  Also called "androconia."

Segment: A distinct body region.  Caterpillars and the abdomens of butterflies are both comprised of many segments.

Sepal: A structure on the outermost part of a flower, appearing like a small leaf or a petal.  A group of sepals enclose the developing flower bud and later open when the flower is mature.

Seta (pl. Setae): The hairlike structure commonly found on caterpillars and other insects.

Silk: The threads produced by the specialized salivary glands of a caterpillar.

Silk girdle: A silken support stucture made by some caterpillars when preparing to pupate.  The silk girdle will hold the pupa in an upright position attached to a twig, stem, etc.

Species: A group of individuals biologically capable of interbreeding and which have a common ancestor.

Spine: A thin, rigid, specialized structure on some caterpillars which provides some degree of protection.

Sphragis: A waxy secretion produced during mating by male Parnassian butterflies.  It contains sperm and important nutrients, and is placed at the tip of his mate's abdomen.  It remains in place after mating, and prevents the female from mating again.  It can sometimes be seen still in place on collected female specimens.  In the picture, the sphragis is the heart-shaped attachment at the tip of the abdomen.[image]

Stigma: A section of scent scales located on the forewing of a male butterfly (specifically Hairstreaks and Skippers) that produces pheromones, useful in attracting females.  The black streak on each forewing of this skipper is a stigma. [image]

Tail(butterfly): A thin, relatively short extension of the rear of the hindwing.  In some species, such as the Hairstreaks, it is thought to mimic insect antennae and thus mislead bird predators into biting at the wrong end and only getting a mouthful of wing while the butterfly escapes in the opposite direction.

Tail (caterpillar): A loose term used to describe any noticeable extension at the rear of the caterpillar.

Temperate: Refers to the geographical region or zone located between the arctic and the tropics.  It is characterized by warm summers and cold winters.

Territorial: To defend a defined area from intruders.  Territories are usually established and defended by the males of a given species.

Thorax: One of the three main regions comprising an insect.  It is located between the head and the abdomen and is where the legs and/or wings are attached.

Tibial tuft: A group of specialized hairs on the tibia (fourth segment up) of the hind leg of some male butterflies, especially Skippers. The hairs are used to help direct pheromone towards a female during courtship.

Tubercle: A small, raised bump on a caterpillar that often bears a spine.