(the life stages of a monarch butterfly)
and photos by Rose Franklin
February 10, 2001
is the series of developmental stages insects go through
to become adults. Butterflies and moths have four stages of
life: egg, larva (the caterpillar stage), pupa (the chrysalis
phase), and adult. It takes a monarch butterfly just 30 to
40 days to complete its life cycle, with warmer temperatures
generally being responsible for faster development.
females lay their eggs on milkweed, the only plant monarch
caterpillars can eat. The eggs are laid singly and generally
on the undersides of leaves. The eggs are very small (about
the size of the periods at the end of the sentences on this
page) and are whitish in color. Three to six days after the
eggs are deposited, they will hatch.
after hatching, the caterpillar is so small it can barely
be seen. It grows very fast though, feeding on nothing but
milkweed leaves. In just 9 to 14 days it is about 2"
long and is now full grown. A caterpillar has eight pair of
legs. The first three pair of legs will later become the butterfly's
monarch caterpillar sheds its skin five times during the larval
stage. Similar to the way a snake sheds its skin when its
body has outgrown the skin, a caterpillar does the same. A
new, larger skin is always waiting under the one that is shed.
See the caterpillar's shed skin laying just behind its tail
the caterpillar is full grown it usually leaves the milkweed
plant. It crawls (sometimes 30 or 40 feet away from the milkweed)
until it finds a safe place to pupate. The caterpillar makes
a silk-like mat and then attaches its last pair of legs to
the mat. The caterpillar allows itself to drop and then hangs
there, upside down in a J-shape, for about one full day.
caterpillar's skin is shed for the last time as it passes
from the larval (caterpillar) stage to the pupa (chrysalis)
stage of metamorphosis. Under the caterpillar's skin this
time is a jade green casing which is called a chrysalis. Inside
the chrysalis, which is only about an inch long, the caterpillar
will miraculously transform into a beautiful butterfly.
after the skin is shed, the chrysalis is very soft. Within
an hour though, it hardens to become a protective shell for
the caterpillar inside. Looking at picture, you can still
see the ribbed body of caterpillar in the newly formed chrysalis
on the left. The chrysalis on the right has hardened to become
a beautiful jade green shell. Dramatic changes occur inside
the chrysalis. The mouth parts must go from being those required
for chewing (what the caterpillar needed to eat milkweed leaves)
to what a butterfly will need: a straw-like tongue used for
sipping nectar from flowers. And a creepy, crawling insect
will become a flying insect, one of the most beautiful insects
In just 9 to 14 days the transformation from caterpillar to
butterfly is complete. Through the chrysalis, you can now
see the orange and black wings of the monarch butterfly.
With no visible signs to signal the emergence
of the butterfly from its chrysalis, the chrysalis suddenly
cracks open and out comes the monarch butterfly. Its wings
are tiny, crumpled, and wet. The butterfly clings to its empty
chrysalis shell as hemolymph, the blood-like substance of
insects, is pumped through its body. As the hemolymph fills
the monarch's body and wings, they enlarge. Right now, this
monarch is extremely vulnerable to predators because it is
not yet able to fly.
one hour after emerging from its chrysalis, the monarch's
wings are full-sized, dry, and ready for flying. Here a newly
emerged monarch uses it straw-like tongue, called a proboscis,
to sip nectar from hardy ageratum (Eupatorium coelestinum).
Four to six days after emerging from its chrysalis, a monarch
butterfly is old enough to mate.....and so begins the life
cycle of of the next generation.