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Metamorphosis is a process some animals go through to become adults. It is a series of physical changes. Metamorphosis is especially common in insects. Genes and chemicals called hormones control the process.
Many insects go through four stages of metamorphosis: egg, larva, pupa, and adult. An insect
hatches from an egg into a wormlike larva. Caterpillars and maggots…
A female Monarch butterfly deposits an egg onto the underside of a milkweed (swan plant) leaf.
A Monarch butterfly egg on the stem of a Swan Plant milkweed. This egg (about the size of an aphid) takes eight days to hatch.
Monarch Caterpillar— First Instar.
Monarch Caterpillar— Second Instar.
This Monarch caterpillar, now into its fifth instar and about 50 mm long, has just shed its skin. The skin, which can be seen lying on the leaf behind it, is usually eaten by the caterpillar shortly after moulting. This caterpillar's next moult will result in a chrysalis.
Monarch caterpillar on a Swan Plant milkweed, fifth instar, about 55 mm long and close to pupation. It is now about three weeks old. however this time-span depends very much on temperature and can vary considerably. When they are ready to pupate the caterpillars tend to wander around, sometimes relatively far afield, presumably in search of a suitable chrysalis-friendly site.
The Monarch caterpillar readies itself for pupation. It has spun a cushion of silk by which it attaches itself to a suitable surface and hangs head-down in a J-shape.
After being suspended from its silk cushion for about 18 hours the Monarch caterpillar starts to straighten out. This is the prelude to shedding its larval skin for the last time. Look carefully at the image and you will see the skin just starting to split behind its head before being pushed upward.
By wriggling, as well as rhythmically contracting and expanding, the Monarch larva (caterpillar) pushes its skin upwards. The jade green pupa (chrysalis), at this stage still very soft, can now clearly be seen.
The pupa now starts wriggling and gyrating energetically to finally dislodge its skin. This Monarch took 12 minutes to complete the moulting process.
This beautiful new jade-coloured Monarch pupa is still soft and wrinkled. Some areas of the adult butterfly-to-be are already apparent. Within the next 1 to 2 hours its casing will harden, smooth out and assume the familiar shape of a mature chrysalis.
The Monarch chrysalis, now smooth with a hard wax-like casing, is a lovely jade green colour with gold spots, hence the name 'chrysalis', from the greek word 'chrysos' for gold.
Shortly before the butterfly is due to emerge the Monarch chrysalis darkens significantly and the orange colour of the wings can be clearly seen through its casing.
The transparent casing of the chrysalis has now cracked open and the Monarch butterfly is emerging, clinging with its legs to the casing to protect itself from falling to the ground.
The pupal stage of the Monarch is usually from 10 to 14 days long. However the time-frame is dependent on the season and the ambient temperature. This pupal stage lasted for 23 days.
Still clinging to the empty shell the damp Monarch butterfly pumps fluid (haemolymph) from its distended body into its wings. In this photo the wings are slowly expanding but are still quite stubby and wrinkled
Seven minutes have elapsed since this adult Monarch butterfly emerged from its chrysalis. The butterfly's wings have expanded but have yet to harden properly.
A newly emerged adult Monarch butterfly, its wings fully expanded and by now probably fully hardened and functional, slowly makes its way upwards towards a high point on the Swan Plant milkweed.
About two hours after emerging from its chrysalis this beautiful adult Monarch spreads its wings in preparation for its first flight.
The butterfly in this photo is a male. Males have a clearly visible black spot on each hind wing from which pheromones are released.
Freshly emerged from her chrysalis this female Monarch will soon make her first flight.
The webbing on a female's wings is thicker than the webbing on a male's wings and females do not have the black spots on the hind wings that are a characteristic of males