
Rearing caterpillars
There are over 140,000 species of
Butterfly and Moth (Lepidoptera) in the World. They include some of the
largest and most beautiful insects to some of the smallest and most
easily over-looked (unless you're an entomologist). Caterpillars are
the main feeding stage in the life cycle of butterflies and moths, and
make one of the best "Creepy Crawly" pets.
Obtaining caterpillars
Caterpillars
of many different moth and butterfly species can be obtained by post
from many good entomological suppliers. However, many excellent
caterpillars can be found by searching plants or bushes during spring
and early summer. When you find a caterpillar remove the plant stem
that it is feeding on and place this is a suitable carrying vessel (eg.
jam jar or sweet jar - with a lid!). Do not try and pick up the
caterpillar with your fingers as they are quite delicate and many
possess hairs or secretions that will irritate your skin - collecting
the stem they're on is much safer.
Do not take lots of
caterpillars from a particular site, five is probably a maximum and the
number taken depends on the size of enclosure you have prepared at home
before collecting the caterpillars. It is also important that you
identify the plant the caterpillar was found on and also take some
stems to put in the enclosure.
If you find a caterpillar
wandering along the ground then it is either searching for a food plant
or looking for somewhere to pupate. If it is small then it is best not
to collect it unless you know the species of caterpillar and the plant
that it feeds on. Note: there are many, many species of small green
caterpillar and unless you know exactly which one it is then it is
likely to starve to death because you can't provide it with the correct
food plant.
Housing
This depends on the size of
your caterpillars and how big they grow - you may need to re-house your
pets as they get larger. Normally a tall sweet jar will be ideal, drill
some small (i.e. smaller than the caterpillars) holes in the lid (get
an adult to help you) and place the stems of the food plant in a small
jar full of water. It may be a good idea to block the top of the small
jar with cotton wool to stop your pets falling in and drowning. If your
caterpillars are very small then you can use a block of oasis (a type
of hard green sponge used for flower arranging) soaked in water and
with the stems pushed into it instead. Once the food plant is placed in
the larger jar then you can gently introduce your caterpillars - again
using the stem they are sitting on. It is also an idea to place a twig
in the large jar so that should the caterpillars fall of the stems they
can climb up the twig back to their food plants.
If you have
a tropical species which you ordered from a supplier then it is best to
keep them indoors and they may even require more specialised conditions
(consult your supplier). If you found your caterpillar outside your
house then you can keep your cage outside however you must be very
careful that it will not blow over in the wind or fill with water when
it rains.
You should spray the cage lightly with water once
a day or so, however avoid large quantities of condensation forming on
the inside of the container. Caterpillars can easily drown in
condensation, remember that to caterpillars, a blob of water is very
much like a lump of syrup.
Feeding
The majority
of caterpillars are herbivores (ie they eat vegetation) although many
will become cannibals if not given enough food plant. Aside from
cannibalistic tendencies some caterpillars will kill and eat
caterpillars of other species of moth and butterfly and it is best to
keep them singularly (e.g. Anthocharis cardamines - the Orange Tip Butterfly).
Caterpillars
are very particular about what they eat. Individual caterpillar species
have a particular type of plant (or family of plants) that it is
associated with. Caterpillars will only eat very specific plants, which
is why you must remember what plant you collected the
caterpillar from - it is a good idea to identify the plant from a book
or collect and press a stem for reference as your caterpillar grows.
As
your caterpillars grow they will require more and more food so it is a
good idea to make sure you have a good supply of the food plant before
contemplating keeping the caterpillar. Remember that the larger the
caterpillars get the more they will eat. Caterpillars increase in size
by moulting so don't be concerned if you see some with small bits of
their old skin still attached.
As soon as most of the food
plant has been eaten or if it starts to wilt you must change it for
fresh leaves etc. The replacement food should be exactly the same plant
as before otherwise your caterpillar may not eat it. It is also a good
idea to wash the food plant thoroughly before giving it to your pets. I
cannot stress enough how important it is that you feed your caterpillar
the correct food plant.
Pupation
All know
caterpillars must pupate as a chrysalis or pupae before becoming a
butterfly or moth (imago). During pupation almost all of the
caterpillar is broken down and the resulting 'nutrient soup' rebuilt
into the body of the adult insect. When the caterpillars are full-grown
they should be provided with suitable pupation sites. Butterfly
caterpillars should be given stems and branches from which to suspend
their pupae. Moth caterpillars producing subterranean larvae should be
provided with a thick layer of damp earth. Other larvae should be
provided with foliage or bark depending on the species. If you are
unsure of your caterpillar's requirements it is best to present them
with a choice of pupation sites. Pupae that have formed during the
spring or early summer should hatch within a few weeks. Pupae that
formed during the autumn will over-winter and should be removed from
the cage and stored to prevent them drying out or going mouldy. The
pupae should be placed in layers of earth in small sealed containers;
these should be kept in a cool but frost-free place until the following
spring. In spring the pupae should be slightly embedded into a layer of
earth or placed between the grooves of a sheet of corrugated cardboard.
They should be misted with water occasionally to produce a humid
atmosphere and this can be used to induce the emergence of adults.
Emergence
When
the adults are about to emerge you should place a number of twigs and
stems in the emergence tank. The twigs are required by the butterflies
and moths to climb up before expanding and drying their wings. If no
suitable supports are available then your butterflies and moths will
have deformed wings and be unable to fly. If you collected your
caterpillars from the wild then you should release the emerged adults
(or imagos) in the same area as you collected the caterpillars. When
releasing butterflies and especially moths (during the day) make sure
that they are released in secluded areas so are not immediately eaten
by birds. http://www.whatsthiscaterpillar.co.uk/ is a great site for identifying caterpillars
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