The Hercules Beetle and Its Captive Breeding and Rearing
By Kay
Getting started
The following are necessary for the captive breeding or rearing of the beetle:
1) An imago pair (or several larvae);
2) Containers for breeding or rearing;
3) Food for imagoes; and
4) Substrate for breeding or rearing.
Instructions
1) Obtain an imago pair (or several larvae) on the following criteria:
a) For choosing wild-caught imagoes, avoid older individuals or the ones with any scar,
injury or missing part; and
b) For choosing captive reared imagoes, avoid individuals of 8 months or older.
2) Oviposition requires some space, ideally, a capacity of 45-120 liters. An example
is a fish tank, and a lid is a must to stop the imagoes from escaping. The lid should
have tiny air holes. The breeding container should be placed away from direct
sunlight.
�� Substrate should be pressed hard against the bottom of the container, up to
10-15 cm depth. Then, add another 10 cm depth of substrate, unpressed,
to the top of the hard-pressed layer. Often times, the female imago prefers
depth and deposits eggs inside the hard-pressed bottom layer.
�� It is good to place several small tree branches or wood sticks on the surface
of the substrate. In case imagoes turn upside down on their backs, they can
easily get up by holding these.
�� Then, put an imago pair into the container. Feed them regularly (for food,
see 3)). For species (e.g. Chalcosoma) whose male imago is vicious, put a
mated female imago alone into the container. Hand pairing would be good
for mating right under your eyes.
�� The breeding temperatures should be kept at 20-25 (?) degrees Celsius, those in
their mating season in Guadeloupe, and the substrate should
be kept moisten adequately.
3) For maintaining imagoes, a pealed banana serves as an ideal food. It is better to
place its pieces or slices on a small tray instead of applying them directly on the
substrate. This prevents them from spoiling faster or avoids an occurrence of fruit
flies or scavenging mites. A pealed apple or a peach also serves as a suitable food.
There are ready-made 'beetle' foods (e.g. jelly) available in some countries.
4) See BREEDING AND REARING SUBSTRATE.
Rearing larvae
One or two months after the imago pair are put into the breeding container, the substrate should be examined carefully to see if eggs have been deposited or larvae have already hatched. If so, the imagoes should be taken out of the container. On the other hand, the eggs or the larvae can be kept in the container until they become second-instar (L2). To obtain more eggs, the imago pair can be put into another breeding container. To gain a maximum larval growth, keep males separated from females at L2 stage, and transfer the males singly into rearing containers of about 10 liter capacity. However, the males can be reared together in a fairly large container (e.g. 60-120 liters) or can be put singly into a smaller container of less than 10 liters at the sacrifice of their maximum growth. Females can be reared together in a large container. However, the fewer in number, the larger they seem to grow. But again, for their maximum growth, female also should be put singly into containers of about 5 liter capacity.
Substrate needs to be changed from time to time. For example, when I was rearing a special, large male larva in a 40 liter container, I changed the rearing substrate every 6 months over the course of a larval period of about one and a half years or until the larvae turned noticeably yellowish in color. However, when a smaller container is used for rearing a male larva, you need to change rearing substrates more often. A reliable sign for a change is larva's dung. If it becomes noticeable, then substrate should be changed. For changing substrates, it is safer to lay newly fermented substrate at the bottom of the container, and then place over it the substrate which was left over by the larvae after removing the larva's dung. Use of a sieve is good for its removal. To keep the substrate well-ventilated, it should not be pressed hard. The capacity ratio of the former to the latter is 2-to-1. If the larva stays in the upper layer for a while, then you can tell that it may not like the new substrate and can change it. Also, by so doing, beetle's symbiotic bacteria would grow fast into the new substrate and would promote an ideal feeding environment for better larval growth (Kojima, 2000). For females, rearing substrates should be changed when their dung appears noticeable in the substrate. From the author's rearing, the duration of the larval periods are: Male: 12-18 months; Female: 12 months.
In Japan, there is a breeding technique practiced widely on this species. When larvae are singly reared, the females tend to emerge much earlier than the males. Sometimes, the gap can be over 12 months. Although the imago of this species has a rather long life of 6-12 months from their emergence, this occasionally makes it difficult for a breeder to mate them for the following generation. To avoid this, I would suggest that at least one large container should be prepared where both several male and female larvae would be put together until their emergence. By so doing, the females and the males would emerge around the same time, which makes it easy to mate them. H. Kojima points out that female larvae's pupation hormone might prompt the male counterparts in the surroundings to undergo pupation simultaneously. This rearing method, however, would not guarantee a maximum growth potential of the male or the female. In other words, for rearing the largest male or female, they should be reared singly in a container of a large capacity. There are several other effective rearing methods, but this is a solid, safe practice to win a best result.
Larva sexing
For sexing, click here.
Maintaining pupae
After larvae turn noticeably yellowish in color, stop changing rearing substrates. It is recommended that at this stage, the substrate should be compacted. When the substrate is kept loose, the mature third-instar larvae might start to wander around to find a place hard enough for cell making and start using the stored energy for pupation and emergence and might die in the worse case (Campbell, pers. commu., 2009). If everything goes well, the larvae will soon make pupation chambers under the substrate in which they undergo pupation. Or if you have noticed any hard part in the substrate while changing substrates, you can tell that it would probably be the wall of a pupation chamber that the larva is making or has made. If this happens, do not touch or disturb the container any longer; put it back to its original place; and wait until the imago emerge naturally from the substrate. It may take several months. When a see-through container is used for rearing, a pre-pupa or pupa may be visible through its wall. The larva often makes a pupation chamber against the wall of the container. To see if the larva makes a pupation chamber or undergoes pupation, handle its container gently.
Breeding
Newly-emerged imagoes need 4 or more months for their maturity. After that, hand pairing is useful for mating. The process on Getting started can be repeated.
