Hercules Beetle Rearing Guide — Complete Care from Larva to Adult

The Hercules beetle is known as the world's largest rhinoceros beetle, with maximum body length sometimes exceeding 180mm. Native to Central and South America, this species boasts high popularity both domestically and internationally due to its overwhelming presence and beautiful coloration. The difficulty level of rearing is moderate, but the long larval period makes it a patience-demanding endeavor.

Basic Information on Hercules Beetles

The Hercules beetle has several subspecies, with the most popular being Hercules hercules (the nominate subspecies). Other subspecies include rickyi, septentrionalis, and ecuatorianus, which differ in horn shape and body coloration. Males have long head and thoracic horns, while females lack horns. Adult lifespan is approximately 6 months to 1 year, with males tending to be slightly shorter-lived. The larval period lasts 12 to 18 months, and in some cases can exceed 2 years or more. Since this is a foreign species of rhinoceros beetle, if it escapes from captivity, there is a risk of impact on Japan's ecosystem. Implement thorough escape prevention measures, and in any case, responsibly manage the insects so they are not released into the wild.

Larval Rearing Methods

Hercules beetle larvae grow by eating fermented broadleaf tree sawdust called "kabuto mat." First to second instar larvae are managed in 800ml to 1400ml rearing containers, and when they reach the third instar, they are moved to larger containers (10 liters or more for males, 5 liters or more for females). Moisture content of the mat is important—the appropriate level is when the mat barely drips water when squeezed by hand and the squeezed form barely holds its shape. Mat replacement is recommended every 2 to 3 months, and when feces become noticeable, it's time to replace it. When replacing, leaving about one-third of the old mat and mixing it with new mat helps reduce stress on the larvae. The optimal temperature is 20 to 25°C, and temperatures sustained at 28°C or above cause weakening. Especially during summer, management in a temperature-controlled wine cooler or air-conditioned room is necessary.

Management from Pupation to Emergence

When third instar larvae grow sufficiently, they begin to construct a pupal chamber (yōshitsu). During this period, refrain from replacing the mat and avoid moving the container. If the pupal chamber is damaged, use an artificial pupal chamber instead. Carve out an elliptical chamber from oasis (horticultural water-absorbing sponge) and use it with appropriate watering. The pupal period lasts approximately 2 to 3 months, during which careful attention must be paid to avoid vibrations or impacts. After emergence, the beetle does not immediately eat food—it takes 1 to 2 months before it begins feeding (kōshoku). This period is called the maturation period, an important time when the internal body structure hardens. Even after confirming emergence, the ideal approach is to wait for the beetle to emerge on its own rather than excavating it immediately.

Adult Rearing and Feeding

Once feeding begins, provide insect jelly (high-protein jelly recommended). Replace the 16g cup jelly at a pace of one cup every 1 to 2 days. Use a large rearing case (width 30cm or more) and lay about 5cm of broadleaf or conifer tree mat. It is important to place bark or perches inside to prevent overturning. Hercules beetles often cannot right themselves when overturned and may exhaust their strength and die. The optimal temperature is 22 to 26°C, and high temperatures shorten lifespan. Maintain relatively high humidity but ensure adequate ventilation to prevent excessive moisture. If males and females are housed together, the male may injure the female with his horns, so keep them separate except during mating.

Obtain Well-Pedigreed Larvae from Br-Choku

Genetics play a major role in raising large Hercules beetles. Through Br-Choku, you can purchase larvae from breeders who specialize in Hercules beetle breeding, with clear information on parent insect size and pedigree. Larvae obtained from large-sized male lineages have the potential to develop into large individuals exceeding 150mm with proper rearing management. Breeders also share detailed know-how about mat brands and temperature management techniques, so those aiming for large individuals are encouraged to consult with them.