an Inside Look at the Life Cycle of Butterflies
are a staggering number of butterflies and moths in the world.
A 2003 survey suggests there are nearly 265,000 species. They
are found in a variety of habitats and some species, like the
monarch butterfly, migrate over great distances.
butterflies and moths are arthropods and are classified as Lepidoptera;
a name derived from the Greek words meaning “scale”
and “wing.” Lepidoptera are different from other
insects. Their entire bodies are covered with overlapping scales,
much like shingles on a roof. The scales are so small and so
thin that it would take more than half a million of them stacked
on top of one another to reach an inch in height.
all insects, butterflies and moths have three body parts: head,
thorax and abdomen. On the head are two compound eyes, a pair
of antennae and a coiled feeding tube or proboscis. The antennae
are sense organs used for smelling and for balance. An adult
butterfly has no jaws, so it uses its proboscis to sip liquid
from flowers, other insects, decaying fruit, fermenting sap
or even decaying carcasses. The compound eyes of butterflies
and moths are sensitive to color and movement and also can see
single feature separates butterflies from moths, but there are
a few general ways to distinguish between the two. Butterflies
typically fly by day; moths tend to fly at night. Butterflies
hold their colorful wings upright over their backs. Moths hold
their wings parallel to their bodies. The antennae of butterflies
have knobs on the ends. Moths’ antennae are more intricate,
sometimes feather-like, structures.
a butterfly’s life
A butterfly’s lifecycle is one of constant change known
as metamorphosis. The lifecycle of a butterfly consists of four
distinct phases: egg, larva, pupa and adult (or imago).
the search for a mate, butterflies can recognize potential partners
and possible rivals through a combination of color, wing beat
speed, flight patterns and pheromones. Pheromones are chemicals
that stimulate excitement or arousal and are produced by male
butterflies and female moths. The male butterfly flutters around
the female, waving his wings and releasing pheromones. The male
and female will alight and link together in a tail-to-tail position.
fertilized female finds an appropriate host plant by sight and
then tests it by smell using special sensors on her feet. Her
offspring will only be able to eat the foliage of specific plants,
so she must select the correct plant or her children will starve.
Different species of butterflies lay eggs differently; some
lay eggs singly, some lay eggs in clumps and others may scatter
eggs while in flight. As the eggs get ready to hatch, they turn
dark and the caterpillar inside can be seen.
it’s ready to hatch the larva (or caterpillar) inside
the egg cuts a circle in the egg with its jaws and emerges –
an absolute eating machine. The job of the caterpillar is to
eat, grow and not get eaten in the process. This larval stage
may last from 12 days to eight weeks or more, depending on the
species. As the caterpillar grows larger, its exoskeleton becomes
too small. The larva grows a new, soft skin beneath the outer
one and then sheds the upper skin. Caterpillars molt an average
of five times before moving on to the next phase of its development.
are slow-moving morsels of protein and fat and are tempting
treats to a variety of other animals like birds, bats, lizards,
frogs and even other insects. As a result, caterpillars have
adapted a variety of strategies to avoid becoming an easy meal.
Some caterpillars are camouflaged; others are poisonous or very
distasteful and advertise this fact with bright coloration.
Some have developed displays like false eyes, flash marks and
unpleasant aromas to warn off predators.
its final molt, the caterpillar empties its digestive system
and the exoskeleton seals shut. Some caterpillars weave a silk
girdle around their bodies to help hold them in place while
others enclose themselves entirely in cocoons. When the caterpillar’s
position is secured, it begins to wiggle until the skin along
its back splits. Underneath the caterpillar’s exoskeleton
is a casing, called a chrysalis. The chrysalis is just another
type of exoskeleton. Once the chrysalis casing is exposed to
the air, it hardens. From the outside, the chrysalis looks inert,
but inside it’s a cauldron of activity.
or three weeks later (sometimes longer), a new creature emerges.
emergence of an adult butterfly from its chrysalis is called
eclosion. The emerging insect uses both air pressure and blood
pressure to expand its body spaces. Gravity helps its wings
unfold. Each crumpled wing is actually composed of two thin
sheets, or membranes, that are bonded together with hollow veins
between them. As blood drains into those veins, the folds in
the butterfly’s wings are pulled flat. After 10 or 20
minutes, the wings expand to full size, but the butterfly’s
outer skeleton is still very soft. When the expansion phase
is over, the butterfly holds its wings apart for an hour or
so until they dry and harden. If a butterfly is damaged during
its expansion phase, the unexpanded or injured parts will harden
and the butterfly will be crippled for life.
many species, the male butterflies emerge about a week before
the females. This gives the males time to seek out nectar to
build the energy reserves needed to find a mate. After an adult
butterfly (or imago) emerges, the search for a mate begins and
the entire process is repeated. Adult butterflies can live for
a few weeks to several months; in some species, the adults can
live for up to a year.
In the past, collectors were the biggest threat to rare butterflies.
Today, habitat destruction and pesticide use are the greatest
threats butterflies face. Butterflies and moths are dependent
on specific host feeding plants, some that are considered weeds
by humans. Draining swamps, destroying woods and other natural
living habitats remove the butterflies' basis of life. Pushing
back or removing quantities of butterfly feeding plants has
fatal consequences for them.
numbers of extinct butterfly species have increased. However,
people are learning from their mistakes and efforts to protect
butterflies are underway.
great deal of attention has been given to the destruction of
the world’s rainforests by villagers in other countries
who need to make space for agriculture or need the money from
logging. Many groups are helping to reduce this destruction
by teaching natives to farm butterflies. Butterfly farming helps
to save the rainforest by providing villagers an alternate income
other than clearing virgin tropical forest. Raising insects
to sell is the only incentive some indigenous peoples have to
save their tropical forests. Butterfly specimens come from butterfly
and insect farms in Australia, Asia, North, Central and South
America which breed and supply live and non-live insect specimens
for butterfly houses and insect collectors around the world.
Butterflies and insects live their entire lifespan on these
farms, and produce eggs for the next generation. This profitable
enterprise promotes important habitat conservation, and many
of the butterfly species exhibited in the Butterfly Garden came
to the Aquarium from these farms.
a butterfly garden
Home gardeners can create their own habitats for native butterfly
populations. Providing a habitat for native butterflies is one
way to help regional butterfly populations. The National Wildlife
Federation provides the following tips to help backyard gardeners