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The Breeding/Rearing of Dynastes hercules hercules (page 3)
- Yasuhiko Kasahara -

You will need to change substrates from time to time. You can put gardening black dirt (garden soil) up to 15 cm high from the bottom of the container, and press it hard. The black dirt layer makes it easier for the larvae to make pupal cells in their last larval stage. Note that black dirt is NOT food and you do not have to remove it each time you change rearing substrates. For male larvae, I change the rearing substrate of a 60 liter container every 6 months over the course of a larval period of about one and a half years or until larvae turn noticeably yellowish in colour. However, if you use a smaller container for rearing a male larva, you need to change substrates more often. A reliable sign for a change is larvaís dung. If it becomes noticeable, then you change substrates. When changing substrates, it is safer to lay unused (new) substrate first, and then the used one. Do not press rearing substrate hard in order to keep it well-ventilated. The capacity ratio of the new to the used is 2-to-1. By so doing, the beetle's symbiotic bacteria, if any, would grow steadily in the substrate and promote an ideal feeding environment for better larval growth11. For females, you can change rearing substrates when dung appears noticeable in the substrate. From the author's rearing, the duration of the larval periods are: Male: 12-18 months; and Female: 12 months.

There is a breeding technique on this species. When larvae are singly reared, the females tend to emerge much earlier than the males. Although the imago of this species has a rather long life (8-12 months), it occasionally makes it difficult to mate them for the following generations. To avoid this, I suggest that you prepare at least one large container where you would put both male and female larvae together until their emergence. By so doing, the female and male would emerge around the same time and it makes it easier to mate them. H. Kojima points out that the female larvae of this species might emit a hormone, which prompts the male counterparts in the surroundings to undergo pupation simultaneously. This rearing method, however, would not guarantee maximum growth potential of the male (or female). In other words, if you want to rear the largest male (or female) imagoes, they should be reared singly in containers of a large capacity. There may be exceptional cases, but that is the safest practice to win the best results.
 

rearing substrate
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Figure 3.2  An example of a 60 liter container, filled with rearing substrate

3.3 Larva sexing

For sexing, see the following picture, Figure 3.3.
 

male Dynastes hercules larva - ventral view
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Figure 3.3  A tiny dent may be visible on the 9th abdominal segment of the ventral side of a male larva after its middle L2 stage. There is no dent on a female larva. Besides, an L3 male often exceeds 100 grams in weight when it is fully grown, whereas the female remains below 80 grams.

3.4  Maintaining pupae

After a larva turns noticeably yellowish in colour, stop changing rearing substrates. Some time soon, the larva will make a pupal cell under the substrate and undergo pupation in it. The best advice I can give you at this point is patience: wait until imagoes emerge from the substrate. It may take several months.

3.5  Breeding

Repeat the process: 3.1  Getting started.

(continued on next page)

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