Breeding/Rearing of Goliathus (page 5)
- Karl Meier
Once you have placed the larva in its cell construction container, it is
best not to move or disturb it in any way for at least several weeks.
The larva will actively roam around in the substrate (including at the
surface) for a time (usually 7-10 days, though sometimes more) before it
finally finds a particular spot to its liking, where it will make its cell.
The cell is nearly always created at or near the bottom of the substrate.
Do not disturb the substrate in any way during the time that the larva
is creating its pupal cell, otherwise it may become stressed and damage
it. Like those of most other cetoniines, the larvae of Goliathus
usually will not create a second cell if their first one is damaged, especially
if the damage occurs once the first cell is nearly completed.
of G. goliatus pupal cells placed within a group box in order to
conserve space. Each cell has a marker in front of it which bears
the date on which the larva was collected from the breeding terrarium,
when it was placed in a cell construction box, when the pupal cell was
excavated, and the sex of the larva. Ordinarily, these cells would be shallowly
covered in substrate, but here it has been temporarily cleared away for
courtesy of Karl Meier.
When the larva has ceased to come to the surface for at least several days,
this usually indicates that it has begun work on its cell. Construction
of the cell takes at least several days to complete. Once you are
certain that an adequate amount of time has passed since the larva discontinued
wandering, and are confident that the pupal cell has been finished, you
can very carefully excavate the cell by scooping out the substrate from
around it. It is advisable to wait at least two weeks after wandering
activity has completely ceased before excavating a cell. If you are
rearing a large number of larvae and have only a limited amount of space
for cell construction boxes, you can place the cells
in groups within a single box of the sand/peat substrate, so that you
will have boxes available to other larvae as they become ready to make
their cells. The lid of a box of substrate containing finished pupal
cells should be reasonably well ventilated, otherwise it will retain too
much humidity and eventually lead to the death of the pupae.
female pupa of a G. goliatus X G. orientalis hybrid, here
shown removed from its pupal cell for photography. Note how the legs
and wings are folded. The legs are usually the first part of the
body to begin emerging from the pupal skin. Photo
courtesy of Karl Meier.
The substrate should be allowed to slowly dry somewhat (but not completely)
over time through gradual evaporation, which will mimic progression into
the annual dry season of the beetles' natural habitat. During this
cycle, the beetle will undergo pupation and transform into an adult. Goliathus
always pupates during the dry season, which in many parts of Africa (even
rainforest areas) can be quite dry indeed. As such, an excess of
moisture is dangerous to the pupal stage of Goliathus since they
are not biologically adapted to cope with it during this part of their
life cycle. Total dryness should be avoided however, as this
can lead to desiccation. The pre-pupal stage is especially vulnerable
to desiccation in situations of total dryness. If the substrate eventually
becomes too dry, carefully remove the cells from the substrate and then
thoroughly mix water into the substrate until it is evenly distributed.
In order to avoid adding too much, it is best to mix the water into the
substrate in small increments until the desired level of moisture is reached.
The moisture level for finished pupal cells should only be about half of
the level that was used during the cell construction stage. Re-bury
the cells at the same depth as previously. Shortly after construction
of the pupal cell has been completed, the larva enters the pre-pupal stage.
This stage is characterized by immobility and shrinkage of the larva, and
lasts for several weeks. At the end of this stage, the larval skin
is shed to expose the pupa, which at first is white but gradually darkens
to an amber hue. The pupal stage lasts approximately 8-10 weeks.
After eclosion (emergence from the membranous pupal skin), the beetles
will remain within their cells in a state of hibernation for a period of
3-4 months, awaiting the arrival of the wet season. For several weeks
following eclosion, the beetle's thick exoskeleton gradually hardens and
darkens. The wet season in equatorial west Africa (in Ghana for example)
is roughly from May through October.
However, the weather pattern farther to the south (in Tanzania for example,
which lies below the equator) is the reverse, with the wet months being
roughly from Nov. through April. If the life cycle of your Goliath
beetles happens to be out of sync with the wild population, this is if
no particular importance. So long as they undergo a wet environmental
cycle (active adult, egg, larva, and pupal cell construction) and a semi-dry
environmental cycle (pre-pupa, pupa, and hibernating adult) which have
durations that are approximately the same as that which they would experience
in nature, all should be well. Five to six months after a larva has
made its pupal cell, remove the cell(s) from the slightly moist substrate,
and then thoroughly mix in as much water as is necessary to bring the substrate
back to the same moisture level as when the cell was constructed.
Re-bury the cell in the box of substrate. The added moisture will
slowly permeate the walls of the cell, and this should stimulate the adult
beetle to emerge within a matter of days to weeks. It is best to
allow the beetles to emerge naturally, prompted by the sudden addition
of more moisture to the substrate. As with most other beetle species,
the adults will not all emerge simultaneously. As not all of them
will have made their pupal cells at exactly the same time, some will take
longer than others to emerge. Some adults may emerge a month or more
dense rainforest of Kakum National Park in Ghana, equatorial west Africa.
species found in this country include G. regius and G. cacicus.
subtropical savannah of Tarangire National Park in Tanzania, southeast
Africa. Goliathus species found in this country include G.
albosignatus and G. orientalis.
one or more adults may emerge far in advance of the others. This
may possibly be prompted by sudden changes in atmospheric conditions, such
as the low barometric pressure caused by a passing thunderstorm, and/or
an increase in the humidity of the air.
In captivity, adult
can sometimes live for nearly a year after emerging, although 6-8 months
is average. Longevity in the wild is likely considerably shorter
on average due to factors such as predators and seasonal weather cycles.