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Butterflies Usually
it takes about 10 days for an egg
to hatch. There is an easy exit for
the tiny first caterpillar to escape
from the confines of its egg.
These eggs hatch into very tiny caterpillars,
or larva, which start eating immediately.
First they eat their egg shell which
is the fuel for their journey to find
the food plant. It also may be the
only meal they have before winter
and without it, they won’t survive.
Then they begin feeding on their host
plant. Unlike adult butterflies which
feed on nectar, caterpillars prefer
the leaves of plants. At this stage,
the butterfly is capable of defoliating
your butterfly garden.
A caterpillar is an eating machine.
It consists of a pair of jaws or mandibles
for chewing plant matter followed
by a long gut for digestion. It moves
using three pairs of true legs (like
all insects) and five further pairs
of 'pro legs', sucker like structures
with hooks on the end for gripping
hold of the leaves and stems.
Along the side of the larva are small
openings, spiracles, nine pairs in
all, through which respiration occurs.
A modified set of salivary glands,
spinnerets, produce silk. All butterfly
larvae are hairy, some quite spectacularly
covered with bushes of setae, and
they may well be off-putting to potential
predators.
When first hatched the larva or caterpillar
is very small indeed, just a few millimeters
long. These first larvae look similar
regardless of which species they belong
to. Usually the caterpillar immediately
searches out food and starts to eat,
although some species over winter
at this stage.
Due to the nature of the skeleton
of insects they cannot grow in the
same way that we do. Every so often
the caterpillar sheds its skin so
that it can expand and grow to a larger
size. This process is known as ecdysis
and each time it happens, the caterpillar
moves on to a new instar. Most European
species molt four times and so their
final stage is usually the fifth instar.
Caterpillars feed for a large part
of their time, consuming an ever increasing
amount of food plant as they get rapidly
larger. Some species prefer the cover
of night to avoid unwanted attention,
the Comma, Polygonia c-album, spends
most of its time underneath leaves
for the same reason. Their excrement,
usually called frass, is dropped all
over the place in small lumps.
Caterpillars produce a silken thread
from organs beside their jaws. This
is used for a variety of purposes.
It gives the caterpillars a good hold
on their food plant and some use it
to rest between bouts of feeding.
When a caterpillar is fully grown
it takes time to wander in search
of a suitable pupation site. This
stage is sometimes known as the pre-pupa.
The larva will let all frass clear
its system before pupation.
Different families pupate in different
ways. A Nymphalid (left) spins a silken
pad and hangs head down using its
anal claspers to grip on. A Pierid
(right) however spins a pad then attaches
itself with head upwards, spinning
a silken girdle for support.
A short while after the larva has
attached itself the change to a pupa
begins. It is thought a hormone is
introduced into the system to begin
this process.
The word chrysalis is derived from
a Greek word meaning gold, referring
to the color of some Nymphalid pupae,
whereas pupa is the scientific word
describing this stage of a butterflies
life.
Once the caterpillar has transformed
into a pupa a remarkable process occurs
transforming the contents of the pupa
into an adult butterfly. This can
take as little as two weeks, but some
species over-winter (hibernate) in
this stage, only hatching in the warmth
of spring. As the pupa is unable to
avoid any potential predators they
tend to be quite well camouflaged,
indeed some are form under the ground.
The pupa hangs onto the silken pad
using its cremaster, rather than the
anal claspers of the caterpillar.
Just before the adult butterfly hatches
the pupal skin becomes transparent
and the wing pattern is visible inside.
The chrysalis splits to allow the
adult butterfly to emerge. Much like
the birthing process, the butterfly
pushes itself out of its cocoon to
re-enter the world as a butterfly.
Its body is filled with fluid which
will be pumped into the wings.
Shortly after the wings have been
pumped full of fluid and dried, all
the leftover products of the metamorphosis
are excreted. This is normally a reddish
fluid, the meconium, and has given
rise to fables of showers of blood
when many butterflies hatch together.
With that, the metamorphosis is complete
and butterfly flies off in search
of food and host plant for laying
its own eggs. It’s an amazing
process that says a lot about the
power of life and nature.
I know you want to be able to see
this process for yourself! This is
probably one of the reasons why you
want a butterfly garden. It’s
an amazing teaching tool for children
and adults alike!
So now, where do you start with your
butterfly garden? With a well-thought
out plan!
To
be continue ...
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