Care Sheet - Japanese Rhinoceros Beetle (Trypoxylus dichotomus)

Written by: Richard’s Inverts

*An adult male Japanese Rhinoceros Beetle (Trypoxylus dichotomus ssp. septentrionalis)*

Common Name: Japanese Rhinoceros Beetle
Scientific Name: Trypoxylus dichotomus
Distribution: East Asia

World Record Size:
Wild – 87.3 mm (2012)
Captive Breeding – 91.7 mm (2017)

Egg to adult: 6-8 months
Adult lifespan: 6 months
Pupal stage duration: 1 month
Maturation time of fresh adults: 1 month

Egg incubation duration: 2 week
Rearing temperature: Room temperature (18-25°C)

Distribution data of extant Trypoxylus dichotomus subspecies:

Trypoxylus dichotomus ssp. dichotomus – China
Trypoxylus dichotomus ssp. inchachina – Kumejima Island (Japan)
Trypoxylus dichotomus ssp. politus – Thailand
Trypoxylus dichotomus ssp. septentrionalis – Japan
Trypoxylus dichotomus ssp. shizuae – Tanegashima Island (Japan), Yakushima Island (Japan)
Trypoxylus dichotomus ssp. takarai – Okinawa Island (Japan)
Trypoxylus dichotomus ssp. tuchiyai – Kuchinoerabujima Island (Japan)
Trypoxylus dichotomus ssp. tunobosonis – Taiwan

*An adult male Japanese Rhinoceros Beetle I found in a local park in Tokyo (Trypoxylus dichotomus ssp. septentrionalis)*

Species Description:

The Japanese Rhino Beetle, (Trypoxylus dichotomus) is the largest beetle species found in Japan and is an iconic part of Japanese culture as larvae are sold cheaply in supermarkets and deparment stores (£2-5 / $3-7 each) to be bought and raised by children at home, and in classrooms along with other insects as part of Biology lessons.

The Japanese Rhino Beetle is popularly kept as a “starter species” by beginners due to their very short development time and ease of rearing. Trypoxylus dichotomus is a medium sized beetle that can range between jet-black to maroon-red depending on the subspecies, and possess forked, Y-shaped horns which they use to fight other males in order to secure mating rights with females.

The Japanese Rhino Beetle has a very wide distribution around Eastern Asia, and there are currently 8 different geographically isolated subspecies which all have regional differences such as overall body size, horn shape, and body colour. I have listed the 8 different subspecies along with their distribution above.

Japanese Rhinoceros Beetles in the Wild:

A favourite past-time of children in Japan during their summer holidays is to go to their local parks and woods with their parents in the early hours of the morning to have a chance to witness wild adults feeding on the tree sweet sap of Japanese Oak Trees.

In the wild, new adults of Trypoxylus dichotomus emerge at the start of summer around June, and remain active during the hot summer months to mate and lay eggs, before slowly dying off as the cold weather starts to set in for winter around October (Trypoxylus dichotomus overwinters as larvae).

Adults are nocturnal so they remain hidden under fallen leaves during the day to shelter themselves from the sweltering 35-40 °C summer heat, and begin to emerge and climb up trees to feed on the sweet tree sap and mate several hours after sunset around 10pm. Their activity slows down again around 5am when there is the first sign of light as dawn breaks and crows, their natural predator, start to wake up to hunt for these beetles. However, some adult beetles can still be found feeding on the tree sap, or flying high above the canopy during the day if you are lucky.

*An adult male Japanese Rhinoceros Beetle feeding on tree sap in the wild, along with flower beetles (Trypoxylus dichotomus & Rhomborrhina sp.)*

Food for Beetle Larvae:

As with most stag beetle species (Dynastinae family), the larvae will feed on substrate that is mainly composed of decayed wood of trees in the Beech family (Fabaceae family) which include oaks (Quercus spp.), beech, (Fagus spp.) and chestnut, (Castanea spp.). A general beetle substrate guide that covers the different types of substrates for different types of beetles can be found HERE.

Unlike with stag beetle larvae, a portion of the substrate for rhino beetle larvae can be replaced with decayed leaves of the same tree species if there is a shortage of decayed wood. I recommend that the ratio of leaves should not exceed the ratio of 1:4 (20% : 80%) of leaves to wood respectively.

To raise large adults, home-made Flake Soil should be used instead of wood collected from nature. Flake Soil is the term used for fresh sawdust that has been decayed under controlled conditions with additional protein sources that results in a uniform, earthy substrate that is rich in nutrients.

To view my tried and tested flake soil recipe with a breakdown of tips and tricks, please click HERE.

Food for Adult Beetles:

Adult beetles can be fed on beetle jelly or most sweet fruits such as bananas, apples, mangos, peaches, melons and watermelons to name a few. Adult females should preferably be given fruits that are higher in protein content such as bananas to aid in their egg production.

Foods to avoid for adult beetles are certain types of sugar-water, and fruits high in acidity such as those in the Citrus genus (oranges, lemons, grapefruits, etc.). Fruits that are high in acidity are said to disrupt the pH balance in the gut of some species, potentially leading to refusal to feed after a certain period of time.

**Breeding Trypoxylus dichotomus:**

How to make a breeding box:

Prepare a 20 L box and fill it 70% full with substrate.
Compress the substrate down as hard as you can (use your hands to press it from above).
Lightly fill up to 70% of the container again with substrate.
Place perches on the surface so that the adult beetles can right themselves up if they accidentally flip over.
Place fruits (or beetle jellies) on the surface as well.

Once the breeding box has been completed, place both the male and female Trypoxylus dichotomus together in the breeding box. Leave them together for 7-10 days to ensure that they mate properly. Afterwards, the male can be taken out and kept separately if you wish.

If the male is seen attacking the female, it is a likely sign that they are not sexually mature yet. When this hapens, keep them separately in their own enclosures for a few weeks before attempting again.

How to check for eggs/larvae:

The breeding box can be checked for any eggs and larvae 1 month after the female has been introduced into the breeding box. Find a large box and empty out the substrate from the breeding box into it by flipping it over. Carefully break apart and work through the substrate in order to find the eggs and larvae. They are soft and fragile, so please take care to handle them gently when moving the eggs and larvae.

Raising the larvae:

Larvae should ideally be separated and reared individually to prevent the larvae from getting stressed out by each other (and to prevent any risk of cannibalism in more aggressive species). Communal rearing is possible, provided that plenty of space and substrate is given. Trypoxylus dichotomus can be reared on either wood/flake soil. At the L3 stage, the larvae should be kept in a container that is a minimum of 2000 ml in size.

Pupal stage:

From the moment onwards after the larva constructs a pupal cell, it is important to keep disturbance to a minimum. Please refrain from unnecessarily picking the container up or shaking it. Their pupal period is about 1 month, after which they emerge into an adult beetle.