Housing:
For breeding pairs/groups of adults, a moderately ventilated 10 gallon tub/tank or something similarly sized, with humid substrate 8-10 inches deep is recommended for optimal egg laying (though females will still oviposit in more shallow substrate, and males kept alone don't need much substrate depth or space). The bottom few inches of substrate should be compacted well.
For substrate, it's generally recommended to use mostly flake soil, top soil, finely crushed rotten wood, etc., since these substrates compact well when kept humid (which females like for egg laying), and are nutritious enough to feed L1 larvae if they hatch inside the breeding setup. Some peat or coco coir can be mixed in for moisture retention if necessary, especially if you find the upper layers of your substrate dry out fast, but the lower layers stay very humid, you don't want the lower layers to ever get too wet, as this can rot and kill the eggs.
On top of the substrate you should provide cork bark tube hides or even small logs for adults to cling to and climb on. If they have nothing to grab onto, adult beetles can fall onto their backs and may be unable to turn themselves over, which can be fatal.
Generally you only want one male in an enclosure at a time, as they can be very territorial and may injure each other. Additionally, no more than two adult females should be kept in a breeding bin, any more than that and the females can injure each other's eggs by digging around in too cramped an enclosure.
For larvae, L1s can be housed comfortably in 4-5 oz deli cups. I'd recommend 8 oz deli cups for L2s, and 16-24 oz cups for L3s. They don't need a ton of space, and can find food more easily in a smaller setup. Larvae are typically reared separately like this, and it's easier to feed and monitor each larva properly when kept isolated, especially when you're starting out breeding this genus.
However, it is possible to rear them communally in a large enough tub, preferably one gallon for each larva inside. As long as larvae of the same instar are housed together, and they're fed frequently enough, rearing them communally can be done (though if different instars are housed together, or you skimp on feeding, some cannibalism may occur).
L1 larvae should be kept on flake soil or crushed rotten wood, but after L1 they can be kept on coconut fiber, sphagnum peat, etc., they don't require a nutrient rich substrate because after L1, they become carnivorous. You can still keep them on flake soil if you want, but it's unnecessary in terms of nutrition for the larva's development.
Larvae should be kept humid, but not wet, and with minimal to moderate ventilation.
Substrate should be changed every couple of weeks or so as it becomes filled with frass and/or fragments of leftover food. Failure to change and replace substrate when it becomes dirty can result in sickly larvae and potentially death. Frequency of substrate replacement really depends on just how quickly said substrate becomes dirty, if you're on top of preventing leftovers from accumulating, and the substrate isn't completely frass filled, you may need to change your substrate less than other keepers do.
Clay substrate will be required for the larvae to build pupal cells, which I'll explain more in depth below in the Breeding/Life cycle section.
Diet:
L1 larvae feed on rotting wood primarily for their first couple weeks, but soon afterwards they become more protein hungry, and should be fed dog/cat/fish food (koi pellets being the most recommended diet), and/or live/prekilled invertebrates.
Once they hit L2 they mainly consume protein matter, and do not require rotten wood from here on out (which is the entire reason they're legal to keep in the US now, they don't need ANY plant matter in their diet past L2, and can't survive without protein). Obviously the L3 are also carnivorous.
Larvae should be fed every 2-3 days, and should only be fed as much as they'll eat within that time frame. Feeding too much will result in rotten leftovers becoming mixed into the substrate, which can pose health problems for the larvae. Feeding too little or too infrequently can result in stunted larvae or even starvation and death.
Adult beetles will feed on soft fruits like banana, sugar water, diluted maple syrup, and/or beetle jellies.
Temperature:
Generally it's recommended to keep these at around 74-80F°. They're a tropical genus, and like being kept warm, though they can handle temporary dips into the 60s and lower 70s, and may handle being kept a bit warmer as well.
Breeding/Life Cycle:
Adults can live 6-12 months under optimal conditions, as long as food is always available. Around 4-6 weeks after mating, females start ovipositing, usually in the lowest layers of the substrate. Females can lay anywhere from 40-100 eggs each, though 40-60 is considered a normal amount. These eggs are laid within little capsules of compacted substrate, and hatch in as little as 10-14 days after being laid. It's advised that you don't dig for the eggs, which are fragile and can be easily damaged, instead wait for larvae to hatch, and remove them as you find them in the upper, non-compacted layers of the substrate (again, you don't want to dig through the lower, compacted layer of substrate where all the eggs are, as you may damage and kill some eggs in the process).
One thing to watch out for is excessive numbers of grain mites, nematodes, etc., as a result of rotting leftiver food being mixed in with the substrate. If pest numbers start getting high, the substrate should be completely replaced, the enclosure cleaned, and the amount of food offered adjusted as well. Adding predatory mites to the substrate mix can help prevent certain pest buildups.
After the L3 larvae have grown quite a bit and are finished developing, they will enter a restless "wandering phase", in which they stop eating completely, and wander around on top of their substrate and try to escape their enclosure by any means necessary. If you notice this behavior persists for longer than 24 hours, and adding fresh food or cleaning dirty substrate doesn't fix this, it means the larva is ready to pupate. (Some mature larvae don't wander, but will just completely stop feeding, if large L3 larvae refuse food for 10 days or longer, it's probably ready pupate as well).
For pupation, the larva should be placed into a container with a clay substrate. Clay mixed with a little sand can work fine too, but the main component of the substrate should be clay/loam. The substrate should be 6 inches deep and compressed, kept humid but not wet.
An inch or so of the top substrate can be replaced with an organic substrate like coco fiber or peat, to make watering and moisture distribution easier, since spraying/pouring water onto clay directly makes mud and can get a little messy. Whereas watering the upper layer, the water should sink into the lower layers of clay more evenly and without causing as much of a mess. However if you're confident in your ability to not overwater the clay substrate directly, then this is unnecessary.
If the larva is ready to pupate, once it's put on the clay substrate it should burrow down and starting making a pupal cell pretty much immediately. It takes about a week for them to construct their pupal cell, which they make out of their spit and the clay, and likely some of their frass as well. The cells should be left alone and undisturbed for at least a couple months, afterwards you can unearth the cells and bury them in plain coconut fiber or peat if you wish to use the excess clay in the pupation container for more larvae. It's important the pupal cells aren't bothered or broken before this time, if the larva hasn't pupated yet, it will likely break out of it's cell from the stress/disturbance, and will not make another one, resulting in it's death.
If all goes well, they should eclose into beetles five months after pupal cell construction. However they'll stay in their cells in a teneral, dormant period for another 3-6 months, depending on the species. After their dormancy period, they'll emerge from their cells, and should start eating right away. They can then be paired up, and the cycle starts anew.
