Page 22 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

How do monarch

butterfl ies live?

The butterfly king makes a spectacular migration,

guided by instinct and an internal compass

he monarch is one of the most recognisable and Metamorphosis Egg
beloved butterflies in the world. It is also one of the Female monarchs lay
Tmost remarkable. Each year, anywhere between 60 The transformation from caterpillar to butterfl y their eggs on milkweed
plants; before laying, the
million and 1 billion of them undertake an incredible winter mother tastes the leaf to
migration from the chilly regions of southern Canada and check it is suitable.
northern USA to southern California and the forests of Larva
western central Mexico – a distance of up to 4,828 The larva hatches four
days after the egg is
kilometres (3,000 miles). laid. It eats the
Monarchs have a wingspan of about 10.4 centimetres nutrient-rich eggshell
followed by the
(four inches), and are identified by their striking black, milkweed leaf.
white and orange colouring. Males and females are almost
identical apart from a dark spot on the hind wing of the
male – a scent gland that produces chemicals to attract
females. As well as being undeniably beautiful, their bright
colouring serves to warn predators that they are foul tasting
and poisonous.
The butterflies actually develop their poisonous quality
as caterpillars. Female monarchs lay their eggs on the toxic Caterpillar
The caterpillar
milkweed plant, and the caterpillars feed exclusively on munches
this. Its glycoside toxins are harmless to the monarch, but voraciously on
milkweed, growing
poisonous to the monarch’s predators. By munching to 5cm (2in) in
milkweed, the caterpillars develop a reservoir of toxins in length and around
3,000 times its
their bodies, which persist in their system beyond original size in just
metamorphosis and make them an ill-advised meal. two weeks.
Most monarchs don’t live longer than about five weeks.
About three to five generations are born between early
spring and the end of summer, but the generation that
emerges from their chrysalises at the start of autumn is
different. This is the “over-wintering” generation, and it’s Hanging J
their job to fly south, away from the freezing North The caterpillar
American winters, and ensure the survival of the species. attaches a wad of
silk to a stem and
The migration is astounding, not only in terms of the hangs upside down
distances the butterflies cover, but also for the fact that they in a “J” position for
about 18 hours.
instinctively know the route, despite never having made
the journey before. Their arrival in Mexico usually coincides
with Día de Muertos (Day of the Dead), one of Mexico’s most Metamorphosis
important holidays. According to local legend, the arriving Over a period of about ten
monarchs are believed to be the souls of the deceased to 14 days, the caterpillar
transforms into a
returning to Earth. butterfly within this hard

Over-wintering monarchs live for up to eight months. protective case.
They embark on the northward journey in early spring,
mating on the wing and laying their eggs on milkweed Chrysalis (pupa) formation
The caterpillar’s exoskeleton splits
plants in the southern United States. Their offspring will from the head upwards and the insect
complete the journey northwards, before the whole cycle wriggles to discard it, leaving behind a
perfect chrysalis.
begins again.

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