Rhinoceros & stag beetles

Heavy mite infestation

SignsClusters of tiny white to brown specks in body joints and leg bases; sluggish movement

PreventionKeep substrate clean and not too wet. Use conifer or anti-mite substrate alongside

Fungus gnats and nematodes

SignsSmall flies or maggots on the substrate surface, white thread-like worms, foul-smelling substrate

PreventionUse a gnat-proof sheet or lidded case. Replace jelly every 2–3 days; leave no rotting matter

Substrate fermentation heat

SignsLarvae surface, substrate steams or smells sour, larval death

PreventionOpen new substrate and let it rest for a week until the heat subsides before use. Keep a thermometer in the case

Failed emergence (eclosion defect)

SignsWings do not close, bent legs or horn, cannot leave the pupal chamber

PreventionDo not move the case during the pupal stage. Avoid substrate that is too dry or too wet

Black spot disease / soft-body disease

SignsBlack spots on the larva, body translucent and soft, not moving or eating

PreventionCaused by overly wet or old substrate. Isolate abnormal larvae and replace the substrate

Weakness from cold or heat

SignsNot moving, legs tucked in, not eating; sudden death above 30°C

PreventionKeep indoors at around 25°C in summer. Never leave outdoors, in a car or in direct sun in midsummer

Fighting injuries

PreventionHouse males singly. Males can kill females during pairing, so separate them after a short time

First aidIsolate in a separate case at once. Lost legs or horns do not regrow but the beetle can live. Apply nothing to the wound

Fall damage

PreventionHandle close to a surface. Do not handle flying individuals outdoors or up high

First aidIf the shell cracks and fluid leaks, keep it still. Leave torn wings as they are and let it rest in a dry place

Flipping over

PreventionAlways provide wood pieces or leaf litter as footholds. Do not leave only a flat substrate surface

First aidPlace a twig nearby so it can right itself. Left too long it dies of exhaustion, so right it as soon as found

Lost tarsi (leg tips)

PreventionDo not let it grip screens or cloth. Never pull it off; wait until it lets go on its own

First aidLost leg parts do not regrow. Climbing becomes hard, so lower footholds and place jelly in a shallow dish nearby

Mite dermatitis

RouteParasitic mites transfer to hands, causing itching and rash

PreventionWash hands after handling. Keep the case clean and treat mites when they appear

Allergy (asthma)

RouteInhaling substrate dust, larval droppings or mold

PreventionWear a mask when changing substrate. Ventilate; see a doctor if symptoms appear

Salmonellosis

RouteSubstrate or jelly residue carried from hands to mouth

PreventionWash hands thoroughly. Do not wash husbandry items in the kitchen

Fungal (mold) infection

RouteInhaling spores from moldy substrate or rotting wood

PreventionSeal moldy substrate in a bag outdoors and discard

Food

• One insect jelly daily. It spoils in summer, so replace every 2–3 days
• Larvae eat fermented substrate. Top up as it drops and replace about monthly
• Banana and apple are fine but spoil fast and attract fungus gnats

Water

• Do not give water; lightly mist the substrate surface (daily to every other day)
• Droplets and puddles cause drowning. They get moisture from jelly

Toys & play

• Climbing logs and perches for natural exercise
• Leaf litter and bark for hiding and footholds
• No 'walks' outside the case; they lead to escapes and falls

Nest, bed & hideout

• Females need firmly packed substrate at least 10 cm deep for egg laying
• Adults need a spot to hide under anti-tipping wood pieces

Bedding & litter

• Adults: about 5 cm of conifer or broadleaf substrate
• Larvae: fermented substrate to 80% of the case
• Remove droppings and debris weekly; replace substrate monthly

Cage / housing material

Plastic case. Gnat-proof sheet or filtered lid with ventilation holes

Size & space

Medium case (30 cm) per adult. Large case, one per individual, for egg laying and larvae

Layout

• Place a jelly dish, climbing log and anti-tipping material
• Moisten substrate until it just holds together when squeezed
• Always keep a thermometer inside the case

Placement notes

• Never in direct sun, direct AC airflow or a car
• Do not keep in a room with insecticide, mosquito coils or air fresheners

Exercise, free-roam & walks

• No walks needed. They move actively inside the case at night
• Check jelly consumption and activity every night
• Handle briefly; they fly, so do not handle outdoors

Temperature & humidity

Temperature20–28°C. Above 30°C or below 10°C is dangerous (foreign species: caution below 15°C too)

Humidity60–70%. Mist just enough to keep the substrate from drying

Summer & winter

• Summer: a cool room around 25°C. Use ice packs or AC
• Winter: many Japanese adults cannot overwinter. Overwintering species go dormant at 15–20°C

Nail trimming

No nail trimming. Instead protect the tarsi: keep legs off cloth and screens, never pull them off

Brushing, skin & coat care

No coat care. Gently remove dirt with a soft, wet brush. Never immerse the body in water

Other care

Scald jelly dish and climbing log weekly. Sun-dry substrate to prevent mites and gnats

Protection from predators

• Place the case where cats and birds cannot knock it over
• Outdoors, beware crows, ants and stray cats
• Cockroaches and ants get in and steal food

Foreign-body ingestion

Store so toddlers cannot put larvae or jelly in their mouths. Keep the substrate clean so beetles do not eat foreign matter (rubber, plastic bits)

Being stepped on

Escaped beetles get stepped on. They are nocturnal and may be on the floor, so check the floor as you walk and move them to another container when cleaning

Getting pinched

A stag beetle's mandibles can draw blood. Arrange the lid and jelly dish so legs or horns cannot get pinched in gaps

Falls

Falls from hands or desks crack the shell. Handle low, close windows in case it flies. Do not put the case on a high shelf

Escape

Always lock the lid; they are strong and push lids up. If one escapes, search windows, curtains and dark corners. Never let foreign species outdoors

Safe release procedure

1. Stay calm, stop moving and bear the pain
2. Lower the beetle onto a surface so its legs touch the ground
3. Press lightly at the base of the mandibles or tap the abdomen to make it let go
4. Once released, return it gently to its case

After the release

Rinse the wound under running water and disinfect. See a dermatologist for deep wounds or persistent swelling

What to tell the vet & what to bring

Almost no clinics treat insects, so consult a specialist shop or experienced keeper. Report the temperature, substrate and any chemical use

Checking consciousness, breathing & heartbeat

• Touch legs or antennae to see if it moves (legs curl in after death)
• Is it active at night? Stillness by day is normal
• Does it move its mouth in response to jelly?

Stopping bleeding

• For leaking body fluid, only press lightly with clean paper
• Do not apply medicine or disinfectant (toxic)
• Rest until the wound dries; keep food nearby

Transport

• Small case with substrate and anti-tipping material, kept dark
• Summer: ice pack on the outside; winter: hand warmer on the outside. Never in direct contact