Housing:
For a breeding enclosure, you can use anything from a gallon Tupperware or a 10 gallon tank, depending on just how big you want your colony to get (and whether communal pupation is a priority or not). No life stages can climb smooth surfaces, so unless any decor goes all the way up to the rim of the enclosure, a tight fitting lid is not necessary.
This genus requires a lot of ventilation in their enclosure, as adults are very sensitive to high air humidity and stuffy, stagnant conditions. Forgoing the use of a lid completely is a viable option, again as long as the substrate and decor/hides are all several inches way from the top rim of the enclosure.
For the substrate, a base of coconut fiber, potting soil, peat, etc. will work nicely for most species, preferably at least an inch or two deep. You can mix in a bit of sand as well, especially if you're planning on going with communal pupation in your setup.
One cultured species (E.depressum) is a psammophile, that actually requires a substrate made up mostly of sand.
If you're going for a horizontal moisture gradient (which I recommend in smaller or shallower setups), around half to two thirds of the substrate should be kept quite dry, with the rest being kept moist.
Alternatively, if the enclosure and substrate is deep enough, (4-6+ inches of substrate), you can use a vertical moisture gradient, keeping the lower third/half of the substrate moist, with the upper layers dry. This will only work in a pretty deep enclosure with a ton of ventilation, as adults are very sensitive to the higher air humidity such a gradient creates. A vertical humidity gradient can allow for larvae to pupate successfully in the main breeding enclosure though, so if you have the room to dedicate a big tank or bin for them, it can make things easier in the long run.
Hides in the form of toilet paper rolls, egg cartons, cork bark, drift wood, fake plants, cholla wood, etc., should be provided for the adults. Keep in mind that the larvae tend to drag hides underground, so be prepared to lift them up from the substrate regularly.
Diet:
Adults and larvae are protein hungry omnivores, and will feed on dog/cat/chick food, dead dried invertebrates, etc..
Fruits and veggies can be offered, but are mostly ignored and used as an occasional source of hydration by adults. Larvae will nibble on fresh root vegetables, but don't tend to eat them with any zeal.
Larvae will also nibble on rotten wood and dead hardwood leaves, but again fairly sparingly when offered protein regularly, and such materials are definitely not a necessary component to their diet.
Temperature:
Room temps from 68-75F° will work nicely for all life stages, and warmer temps in the 75-85F° range will speed up growth and development.
Breeding/Life cycle:
Adults usually live up to 1-2 years under optimal conditions; though it should be noted that they are quite sensitive to humidity fluctuations and overcrowding, which can shorten their lifespans considerably. Adult females lay several dozen eggs soon after maturing, sometimes taking a month or two break between clutches, (some localities could need a winter diapause for consecutive batches of eggs each year). The eggs take about 2-3 weeks to hatch, and the resulting larvae are tiny and agile, thus they often go unnoticed until they molt a few more times.
The larvae take 3-4 months to reach maturity, after which they seek moist substrate to burrow into and make their pupal cells. Like most desert Tenebrionid larvae, pupal cells are constructed by pushing substrate away from themselves until they clear a little room in the dirt. They do not reinforce their pupal cell walls with frass or spit like Scarabaeoid beetles do, so they must build their cells in moist, compressed substrate, otherwise the walls can collapse and kill the pupae within. When the larvae reach maturity, (they'll be a little longer than the adults they came from), it is suggested that you isolate them and place them in minimally ventilated, small deli cups (1-2 oz ones work great) filled with moist (but not wet), compressed substrate. With any luck, they will burrow down and create a pupal cell near the bottom.
Sometimes in a large colony, larvae will attempt to pupate in the moist areas of the enclosure, and through the burrowing actions of their brethren, get pushed up to the surface. These "pre-pupal" larvae are easy to tell apart from other larvae, as they are immobile, and normally curl up into a J shape. They should be removed ASAP and moved to deli cups with a thin, smooth layer of moist coconut fiber. Sometimes they will pupate successfully in these conditions, other times they die, but it's better than leaving them in the main colony, where they will certainly be eaten. You should keep the substrate in the pre-pupal larvae and pupae cups quite humid, but never spray the individuals directly, as contact with water droplets can cause rot/fungal infections, and kill them.
After a week or two of staying in the pre-pupal position, the larvae will molt into pupae. The pupae take only 2-3 weeks to finish development, after which they molt into soft, teneral adults. Once you notice your pupae have turned into adults, or after they claw their way to the surface from their pupal cells, (whichever comes first), you should move them ASAP to well ventilated deli cups with dry substrate, with just a small corner kept moist, and offer them a small amount of food. If the adults stay in their humid pupal setups too long, they will die. You have to move them very gently though, because they are still soft, and their elytra can easily be dented and deformed permanently at this stage.
You can throw fresh adults back into a breeding enclosure once they are fully darkend and their exoskeleton is hard to the touch. To be extra safe, I would recommend keeping the new adults in isolation for up to 2-3 weeks, by that time they should have finished hardening up completely, can be safely be handled, and put back in the main colony.
