The monarch butterfly: Latin (scientific) name is Danaus plexippus – (duh-NAY-us PLEX-ip-us)
The metamorphosis of a monarch takes place as it transforms from the stages of an egg, to a larva, to a pupa, to a butterfly.
Larva – (LAR-vuh), plural, larvae (LAR-vee)
the second stage, after the egg, in metamorphosis. Also known as “caterpillar.”
Molting – the shedding of skin. A monarch larva molts as it grows and becomes too large for its former skin.
Monarchs molt five times in their larval state, which lasts about 9-14 days
Instar – a period between larval molts. There are five of these periods in the growth of a Monarch larva, and the caterpillars are identified by the stage. Time in each stage is temperature dependent.
1st instar— pale, no stripes, black head. 2-6 mm in length, 1-3 days
2nd instar — black, yellow, white bands, yellow triangle on head. 6-9 mm. 1-3 days
3rd instar — black and yellow bands are darker, more distinct. Feeds using cutting motion on leaf edges. 10-14 mm. 1-3 days.
4th instar — banding pattern on the body is more distinct, white spots on the prolegs (the fleshy stubs near the abdomen, which provide stability). Front tentacles: 5 mm. 13-25 mm. 1-3 days
5th instar — vivid stripes, black widens. Plump.Move fast and far as they seek a pupating site. Front tentacles: 11mm. 25-45 mm, 3-5 days
Frass – the waste product of the larvae, called caterpillar poop by most students. Monarch larvae produce a lot of this, especially in their later instars.
Chrysalis – (KRISS-uh-lis); plural, chrysalides (KRISS-uh-lids)
another name for a butterfly pupa. A “cocoon”is a silk web that encloses the pupae of many moths, but not butterflies.
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)
Cremaster – a small stick-like appendage that secures the chrysalis to the silk appendage that was spun at the beginning of the pupation.
Eclosion – an entomological term; the emergence of an adult insect from its pupal case -or- the hatching of a larva from its egg. The monarch swings down and out of the chrysalis, with a swollen abdomen full of hemolymph (fluid). Contractions pump the fluid into the veins of the wings, expanding them. The proboscis — the coiled feeding tube for sucking nectar— is knit together from its two separate pieces. The butterfly will also excrete meconium, a reddish liquid of waste produced by the monarch while it was in a chrysalis. It will hang on the empty chrysalis until the wings are dry and strong (usually at least four hours), and then it is ready to fly.
