Abdomen – (AB-duh-men): the elongate hind part of the body, behind the thorax.

Adaptation – (A-dap-TA-shun): character that enhances the chances an organism will survive and reproduce.

Antenna – (an-TEN-uh), plural, antennae (an-TE-nee): sense organ on an insect’s head. In Monarch larvae, these are often confused with the tentacles or filaments. Larval antennae are very small, while adult ones are much longer.

Aposematic coloration – (AP-uh-suh-MAT-ik): coloration that warns predators of distasteful prey. Asclepias syriaca – (u-SKLEE-pee-us sir-I-uh-kuh): common milkweed, the most common host plant for Monarch larvae in the upper midwestern US. Monarchs also eat other members of the genus Asclepias.

Camouflage – a French word that means to hide or disguise. There are two types of camouflage: protective resemblance and protective coloration. Protective resemblance is when something looks like something else in its environment. Protective coloration is when something has the same color or pattern as its surroundings.

Chemoreceptors – (KEE-moh-ree-SEHP-tors): cells that sense the presence of chemicals and relay that information to the organism. Taste and smell are sensed through chemoreceptors.

Chrysalis – (KRISS-uh-lis), plural, chrysalides (KRISS-uh-lids): another name for a butterfly pupa.

Cocoon – (kuh-KOON): a silk web that encloses the pupae of many moths, but not butterflies.

Compound eye – (kom-pound): an eye made up of thousands of photoreceptor units, known as ommatidia.

Costal margin – (kos-tahl): the area within the leading edge of the wing.

Danaus plexippus – (duh-NAY-us PLEX-uh-pus): the scientific name for a Monarch butterfly.

Dichotomous key – a tool for identifying a species by narrowing down options that limit description to certain features.

Discal cell – (dis-kal): located near the centre of the wing, it’s a noticeably large cell.

Entomologist – a scientist who studies insects. The study of insects is called Entomology.

Exoskeleton – a hard skeleton located on the outside of an invertebrate’s body (in contrast to the internal skeleton of vertebrates) that protects it and serves as a point for muscle attachment.

Forewing – (FOR-wing): either one of the two front wings on an insect with four wings.

Frass – the waste product of larvae, called “caterpillar poop” by most students. Monarch larvae produce a lot of this, especially in their later instars.

Hindwing – (HIND-wing): either one of the two rear wings on an insect with four wings.

Inner margin – the trailing edge along the base of the wing.

Instar – a period between larval molts. There are five of these periods in the growth of a Monarch larva.

Larva – (LAR-vuh), plural, larvae (LAR-vee): the second stage, after the egg, in metamorphosis. Also known as caterpillar. Monarchs molt five times in their larval state, which lasts about 9-14 days.

Metamorphosis – (met-uh-MOR-fuh-sis): series of developmental stages through which insects become adults – a butterfly is transformed from an egg, to a larva/caterpillar, to a pupa, to a butterfly. There are two types of metamorphosis: incomplete (simple) and complete (complex). The four distinct stages of metamorphosis found in butterflies are considered complete metamorphosis. Incomplete metamorphosis does not have a prolonged immobile (pupa) stage.

Migration – movement of an organism or group from one habitat or location to another, usually periodic or seasonal movement of relatively long distance.

Mimicry – harmless animals that look like brightly colored, distasteful animals.

Molt – the process of shedding the skin or exoskeleton. Monarch larvae molt five times.

Outer margin – the outside edge of the wing.

Palp – plural, palpi: paired appendages on an insect head used to sense and test the quality of food.

Phenology – (fe-NOL-o-gee): the science of seasonal changes and their affect on the natural world.

Pheromones – (FAIR-uh-mohns): special chemicals released by some animals to communicate with other members of their species. They may be sensed over long distances and can help mates find each other. They may also help ensure that mating only occurs with other members of the same species.

Photoperiod – the amount of daylight hours.

Proboscis – (pro-BAHS-kiss): the adult Monarch’s feeding tube used for sucking nectar. The proboscis is coiled under the head when not in use.

Pupa – (PU-puh), plural, pupae (PU-pee): the third stage in metamorphosis, after the larval stage. In Monarchs, this stage lasts 8-13 days.

Pupate – to change from a larva (caterpillar) to a pupa (chrysalis).

Scales – overlapping pieces of chitin (the same material of which exoskeletons are made) that insulate butterflies’ bodies and wings, improve their aerodynamics and give them color and markings. Many people think the scales look like fine dust on butterfly wings.

Thorax – middle section of an insect’s body. Wings, if present, and legs are attached to this segment.

Warning coloration – bright colors advertising poisons or other harmful defenses to potential predators. Also called aposematic coloration.


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