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The Breeding/Rearing of Goliathus (page 2)
- Karl Meier -
 
    It is best to use a rather deep substrate for a Goliathus breeding terrarium.  A substrate depth of 25-30 cm is optimal.  The bottom 8 cm of substrate should be firmly compacted by hand, as this can help to encourage egg laying.  Leave the substrate above this compacted layer uncompressed.  A terrarium measuring approximately 50 cm long X 40 cm wide X 60 cm tall works well for large Goliathus species such as G. goliatus and G. regius.  A smaller sized terrarium can be used for G. albosignatus, the adults of which do not exceed about 70 mm.  A simple way to make a strong, lightweight and economical breeding terrarium for Goliathus and other giant beetles is to stack two large, identical plastic storage boxes (minus their original lids) with open ends facing each other.  The bottom box forms the substrate chamber, and the top one serves as a spacious cover.  For ventilation, at least two large holes (approximately 5 cm X 2 cm in size) should be cut into the top of the cover.  Securely attach pieces of window screen  (preferably aluminum, since it will not rust) over the ventilation holes with strong tape that will not readily peel off.
Goliathus breeding terrarium - Image  Karl Meier
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A simple and effective transparent breeding terrarium for Goliathus, made from two large, identical plastic storage boxes.  The bag of sand acts as a weight to hold the top box on securely.  Photo courtesy of Karl Meier.

    Several pieces of thick, flat tree bark (such as cork bark) should be placed on the substrate surface to give the beetles a solid gripping surface.  Without this, the beetles can often become flipped over onto their backs, which can in a matter of hours lead to death by exhaustion as they attempt to right themselves.  The males can be quite aggressive toward each other, and you may find it preferable to keep only one male in the breeding cage at a time.  If you have multiple males, they can be periodically rotated so that each has an opportunity to spend time in the breeding terrarium, which helps to better ensure fertility of the females.  This also prevents the possibility of males injuring each other.  When not in the breeding terrarium, each male can be housed separately in a small plastic box of between 6-8 litres in volume.
 

G. goliatus (females) - Image  Karl Meier
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G. goliatus females (captive reared).  Photo courtesy of Karl Meier.
    Keep no more than two pairs of adults in a breeding terrarium, otherwise the females will likely damage each other's eggs as they burrow.  Like other scarabs, Goliath beetles are extremely strong, and if using a terrarium made from plastic boxes as previously described, place something heavy (a medium-to-large, zipper-seal bag filled with sand works well) on top of the cover box to prevent the possibility of the beetles sliding it off.  Also keep in mind that Goliath beetles are powerful fliers. 

    Unless the surrounding air is extremely dry, it is only rarely necessary to mist the substrate surface with additional water.  Misting the substrate's surface too often or too heavily will cause excess water to seep down to the bottom, which will prove fatal to the eggs.  It is far safer to maintain the proper moisture level by means of water-retaining additives such as peat or coconut coir, as well as keeping ventilation to a minimum.  If condensation forms regularly on the inside walls of the terrarium, this may mean that the humidity is too high, and any supplemental misting of the substrate should either be discontinued or decreased.
 

    Most of the areas in which Goliathus is found remain within a relatively consistent temperature range throughout the year.  In captivity, it is important to maintain a room temperature of between 21-27 degrees Celsius (70-80 degrees Fahrenheit).  Occasional, brief (a day or two) fluctuations slightly above or below this temperature range will do no harm.  However, if there is an extended period in which the temperature is much below 21 degrees C., the eggs and larvae can suffer shock and may have a permanent developmental disruption from which they will not recover.  While maintaining the correct temperature is crucial, no special attention to lighting is required for Goliathus.  General room lighting is adequate, and so long as they are kept warm, the beetles will go about their normal activities.
G. goliatus (male) - Image  Karl Meier
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A male G. goliatus clinging to the base of a tree branch (captive reared).  Photo courtesy of Karl Meier.

    Like many other African cetoniines, the adult stage of Goliathus is primarily a sap flow feeder.  An excellent tree sap substitute can be made by mixing 3 parts brown sugar (preferably dark brown) with 1 part water.  This is stirred together in a large saucepan and heated until it is completely melted and of uniform consistency.  The resulting syrup is then allowed to cool completely, and given to the beetles by soaking it onto ordinary cellulose sponges.  Before using them, the sponges need to be very thoroughly rinsed and wrung out several times because there is an additive on them that keeps them soft while in their packaging.  Make certain not to use sponges that have been treated with any anti-bacterial chemicals, or have been previously exposed to cleaning solutions or other substances.  Cut the sponges into pieces of appropriate size for your situation.  For example, for each pair of beetles, a sponge measuring 6 cm X 6 cm is adequate.  Place the sugar sponge on a small shallow dish (a plastic container lid works well) to help minimize contact with the substrate.  The sponge should be completely rinsed and wrung out with clean tap water every five days and new syrup applied.
 

G. goliatus X G. orientalis hybrid (mating pair) - Image  Karl Meier
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A mating pair of G. goliatus X G. orientalis hybrids (captive reared).
Photo courtesy of Karl Meier.
    Often, the sponges eventually become discolored by a mildew that feeds on the sugar.  Replace the sponge when it becomes either too mildewed or is largely ripped apart by the beetles.  Do not be concerned about using sponges that have become somewhat discolored by the mildew, as it does not appear to be harmful to the beetles at all.  The brown sugar syrup can be kept in a large bottle at room temperature - refrigeration is not necessary.  This syrup also works very well for the adults of other species of Cetoniinae, as well as Dynastinae and Lucanidae, and helps to extend their longevity.

    After mating, Goliathus females usually begin laying eggs within four weeks, although it can sometimes take six weeks or more.  Eggs are always deposited at the lowest level of the substrate.  A sign that egg laying has begun is that the females will begin creating vertical tunnels, the openings of which often collapse inward at the surface, forming sinkholes.  As is the case with the dynastine scarabs, Goliathus deposits its eggs singly within small nodules of substrate which the female has compacted.  When broken open, these nodules reveal the egg resting within a tiny hollow.  The eggs measure approximately 4 mm X 2 mm upon being deposited, but they increase in size and become more spherical as they develop.  Typically, the eggs will hatch 12-14 days after being deposited.  The eggs are rather delicate, and susceptible to damage unless handled very carefully.

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