One of my personal favourites is Blaberus discoidalis, also known simply as the Discoid roach. This species has long been mislabelled as death heads in many zoological reports, so you may sometimes hear people referring to them as false death heads. The scientific name is also occasionally misspelled “discoidales”, but the proper spelling is discoidalis, which is Latin for “orbicular” and occurs in other scientific names. This is another non-climbing, non-flying species that is pretty easy to find on the market. Smallest nymphs measure approximately 4mm by 6mm, and adults are just slightly under 5cm long.
These roaches are extremely shy, but still interesting . They tend to be more active at night, where you can witness them exploring.
For a small to medium-sized colony, a ten gallon aquarium will suffice. This species is unable to climb glass, but it can still make its way up the glued corners of an aquarium. Keep a lid on all your tanks. If you house the roaches in a large Rubbermaid or Sterilite tote, make sure you choose one that has very slick sides. These roaches are able to climb some containers similarly to how crickets can climb storage totes that have just the tiniest bit of texture to them. No substrate is necessary as long as you provide several layers of paper egg cartons for them to hide in. I buy egg flats and then cut them up into different sizes. This makes collecting the roaches easier when you need multiple roaches of a certain size. The babies tend to stay on the smaller pieces of egg cartons while the bigger nymphs are in the larger cuts. Gravid females seem to especially enjoy hiding in paper towel tubes, but they are a pain to get out when you have to remove them when the paper towel tube gets soiled. Be vigilant about keeping the dry food and the moist food separate. It’s a good idea to use shallow food dishes or jar lids. The dry food itself doesn’t need to be in a bowl, but make sure any water crystal gel is contained to keep it clean. Dirty water gel and moistened roach food is usually what attracts flies.
This species likes it warm. I suggest an ambient temperature of around 80 degrees and a warm side of 95-100 degrees F. Cooler temperatures will simply mean slower production.
Discoids may seem difficult for some to get started, but I find this to be a Blaberus trait in general. The key is to provide a constant source of moisture. Premature adult deaths will occur frequently and without warning if you only offer moisture a couple of times a week. Moisture can be supplied in the form of water crystals, fruits, and vegetables. Another alternative is to supply a small bowl of water. This species is less inclined to suffer drownings than others, but make sure to provide a thick flat stick at least 1″ wide leading from the egg cartons to the bottom of the water dish. It’s also wise to make sure the bowl is low enough to allow adults and larger nymphs to access when they stand up. This will help prevent a surge of roaches trying to get to the water all at once. One thing I’ve noticed about Blaberus is that they’re more comfortable eating if you place their food under a hiding spot. I accomplish this by simply putting some smaller pieces of egg carton over their main feeding spot, and then sprinkling any fruits or veggies in between the egg cartons or at the entrances of the paper towel tubes. Cage cleaning is the least stressful with these guys because any babies that accidentally get thrown out will surface on top of the dirty paper towels and catch your attention. Frequency of cleaning depends on the size of your colony. If you keep a colony of about 500 roaches, one thorough cleaning every few months is enough assuming you maintain a clean food/water area. I clean the cage by sweeping the frass up with a small brush–the kitchen kind used for spreading sauces.
I haven’t noticed any particular dietary preferences in Blaberus discoidalis, so I simply offer a little bit of everything. I suggest feeding leafy green vegetables because the scraps will dry out instead of moulding. The scraps also mimic leaf litter for the nymphs to burrow under as well as assist in helping the upturned roach get back on its feet. I recommend keeping sources of protein and carbohydrates available at all times, such as cat food, breakfast cereal, and mixed grains, and then treat them to alternative sources of fruits/vegetables every other day. They show no interest in fish flake food, so opt for other types of protein. If you choose to use cat food, make sure to grind it into a powder or else they will not be able to eat it (even though they want to).
They are great producers, but results will vary according to how well you accommodate their needs. They are ovoviviparous. For best breeding results, you should disturb them as little as possible. Remember that this is a very skittish species that likes to be left alone. Constant disturbance may lead to aborted egg cases. That means don’t count your roaches, don’t look for babies everyday, and don’t lift or move the hides unless you’re doing the occasional cleaning.
I think these work best as feeders because they keep on moving so much. While other roaches dive for cover and remain hidden shortly after being tossed into your tarantula’s cage, discoids will continue to run around and catch attention.