Breeding/Rearing of Goliathus (page 4)
- Karl Meier
Avoid the use of spacious rearing containers, as the larvae of Goliathus
develop best when kept in small ones - in fact, containers that seem almost
too small in proportion to the larvae. Because the larvae feed almost
exclusively on protein-rich pellets rather than decayed plant material,
keeping them in small containers helps to ensure that they are able to
quickly find the pellets, which leads to faster, larger growth. Also,
less food is wasted through spoilage. Small plastic containers with
tight fitting lids (such as are used for food storage) work very well.
Several ventilation holes should be drilled or cut in the lids. Although
the containers need only be large enough for the larvae to be able to turn
around within them, the larvae should be moved to progressively larger
containers as they grow. L1 stage larvae can be kept in a standard,
35 mm film canister with several small ventilation holes pierced in the
lid. A container of 118 ml (4 oz.) works well for L2. 280 ml
(9.5 oz.) is adequate for early to mid L3. Late L3 larvae (except
G. albosignatus, the smallest Goliathus species) are
best kept in a container of at least 708 ml (24 oz.). The lids of
containers used for 3rd instar larvae should always be well secured with
elastic bands, otherwise the larvae may eventually pry them open.
The individual rearing containers can be placed in groups within a large,
open-topped plastic box in order to better keep them together and simplify
Several months after hatching, as full size is attained during the latter
part of the 3rd instar, growth slows down significantly and the larvae
will generally not eat as much per feeding. Decrease the amount of
food pellets as necessary. Substrate in the rearing containers should
be completely replaced immediately if it starts to become infested with
scavenger mites, or if it develops a slight odor (usually after a few weeks,
but variable depending upon the age of the larvae and their feeding activity).
3rd instar Goliathus larva in its rearing container. Ordinarily,
this container would be filled to at least 90% capacity with substrate.
Here, the majority of the substrate has been removed to show the larva
and the new supply of food pellets (soft-moist cat food) that has just
courtesy of Karl Meier.
same rearing container, now filled with substrate and secured with lid
and elastic band. Note the holes that have been made in the lid to
provide ventilation. Photo courtesy of Karl
group of rearing containers placed into a much larger, open-topped plastic
box to keep them gathered together and help simplify routine maintenance.
courtesy of Karl Meier.
Well fed Goliathus larvae can reach impressive weights in the late
3rd instar. The large male larvae of G. goliatus, G. regius
and G. orientalis can reach a weight of approximately
The conditions required for consistently successful pupation in Goliathus
are rather specific, and were a mystery until quite recently. Once
the larvae have completed their growth, they will cease feeding and begin
trying to escape from their rearing containers, pressing against the lid
and often creating a deep trench of compacted substrate around the container's
perimeter. This peculiar wandering at the surface, which also occurs
to varying degrees in other species of Cetoniinae and Dynastinae, takes
place just prior to the building of the pupal
cell. Interestingly, whenever one larva begins this behaviour,
it is not unusual for one or more others in the immediate vicinity to also
do this, apparently in response to a chemical or auditory signal emitted
by the first larva. Most likely, this serves to help synchronize
their pupal cycles, so that they will all emerge as adults at approximately
the same time. When a larva discontinues feeding and shows obvious
signs of wanting to leave its rearing container, it should be transferred
as soon as possible to a container that is large enough for it to have
adequate space in which to construct its pupal cell.
plastic storage boxes (approximately 6 litre capacity), each of which contains
a Goliathus larva that is constructing a pupal cell. A small
ventilation hole is drilled in each of the lids' four corners. Most
larvae will begin making their cells within 7-10 days of being placed in
this special, particularly sandy substrate. Photo
courtesy of Karl Meier.
A plastic box with a tightly-fitting lid and a volume of approximately
2 litres is adequate. Several ventilation holes 1 cm in diameter
should be made in the lid to provide ventilation. The box should
be filled to the very top with substrate. The composition of the
substrate used for Goliathus pupation is of critical importance.
Use a mixture of 60%
fine sand (such as beach or sandbox sand) and 40% peat (or alternatively,
coconut coir). Once prepared, this substrate can be re-used indefinitely
for multiple generations of
Goliathus. The substrate should
be thoroughly mixed together and moistened enough to allow for the larva
to create an oval, structurally sound underground void for making a cell.
The function of adding peat to the mixture is to maintain and distribute
moisture, helping the substrate to stick together and make it possible
for the larva to burrow and construct its cell without the surrounding
substrate collapsing. Without this very sandy, soil-like mixture,
larvae are not able to create solid cells in which to pupate. Cells
which lack the strength which sand affords are at risk of being easily
damaged, and can readily collapse. To prevent the larva from pushing
the lid off of its cell construction box, it is advised that several strong
elastic bands be placed around it to hold the lid down securely.
Each larva must have its own box - a Goliathus larva will not build
a pupal cell if another larva is present in the same container.