Therea spp. (Domino & Question Mark Roaches)

Housing:

Something like a gallon container works well for a starter culture, eventually as their numbers rise, you'll want to move them to a larger enclosure, something 5-10 gallons large. Adults can climb, so a tight lid is recommended. Moderate to high ventilation is recommended.

2-3 inches of substrate should be provided, preferably coconut fiber, potting soil, peat moss, etc., sand is highly advised against. On top of the substrate, you can also provide a 1-2 inch layer of decaying hardwood leaf litter if you want, Therea nymphs will definitely consume leaf litter, however recent evidence suggests this is not a necessity.
No hides are needed, as nymphs and adult females spend most of their time underground, and adults will usually burrow if frightened, especially females. However, some branches and such for the males to climb around on during the day might be appreciated.

These roaches prefer a humidity gradient, with half of the substrate being kept dry, and the other half pretty humid. Both vertical or horizontal gradients work, it's up to you, however ooths do hatch best when kept humid, so a vertical gradient is more likely to keep more ooths humid than a horizontal one. To achieve a vertical humidity gradient, simply pull back the top half of the substrate, and heavily mist or pour water onto the lower half.

DO NOT house multiple Therea spp. together, as they can hybridize and seemingly create fertile hybrid offspring.


Diet:

Dog/cat/chick feed should serve as the staple diet, leaf litter can be offered as well for the nymphs. Most fruits and veggies have gone ignored in my experience.


Temperature:

These roaches will breed when kept anywhere from 70-85F°, but breed best when kept at 75-85F° IME.


Breeding/Life cycle:

Adult Therea typically live for 3-6 months, but apparently female T.olegrandjeani can make it to 9 months* under extraordinary conditions, though by then they've lost their reproductive ability. Females lay oothecae roughly once a week, with T.regularis being the least productive. Each ooth contains around 10-15 eggs, and the females deposit them directly in the substrate. The ooths take around 3-5 months to hatch, and the resulting nymphs take 7-12 months to mature, all depending on how warm you keep them, and how much protein they have access to.

While the nymphs take quite a long time to mature, it's worth it to see the beautiful, yet short lived adults! And eventually, once the colony reaches a decent size, there should be some generation overlap, which means you'll be seeing adults in the enclosure year round. Overall these roaches are pretty easy to care for and breed, and are a good choice for beginner and seasoned Blatticulturists alike!

Species Notes:

Therea bernhardti/petiveriana (Domino Roach):

The ID of the domino roach stock in culture has long been contested, supposedly they're a distinctly different species than true T.petiveriana, larger with different spot shapes and hindwings structure/color. However some of these features are variable, and the original description for bernhardti isn't the best (though the size alone compared to true petiveriana does make it seem a valid species IMO).
In any case, this species is one of the best beginner Corydiids to keep, they're very prolific and hardy, and can handle a wide range of conditions fairly well.

Therea cf. irreperta (Hidden Domino Roach):

This species is a bit unusual for this genus in having relatively long wings on both sexes, capable of flight! Brand new to culture, seems to have standard care needs for the genus, a bit slower growing (like T.regularis).

Therea olegrandjeani (Question Mark Roach):

The smallest of the cultured Therea spp., but perhaps the most interestingly patterned. Very hardy and prolific too, can handle a wide range of conditions.

Therea regularis (Orange Domino Roach):

The slowest breeding and least prolific of the Therea spp. in culture, seems to prefer higher, more consistent heat than the others for decent growth/reproduction. Also a bit more intolerant of filthy conditions. Remains a bit uncommon in culture even though they've been in the hobby for years.