The 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 for 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 routine maintenance.

    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).

G. goliatus X G. orientalis hybrid (3rd instar larva) - Image  Karl Meier
A 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 been added.
Photo courtesy of Karl Meier.
Goliathus rearing container - Image  Karl Meier
The 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 Meier.
Goliathus rearing containers - Image  Karl Meier
A group of rearing containers placed into a much larger, open-topped plastic box to keep them gathered together and help simplify routine maintenance. Photo 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 100 grams.

4. Pupation

    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.

Goliathus cell construction containers - Image  Karl Meier
Stackable 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, Goliathus 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.


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