I have a lobster roach colony going on so I think they are kinda the same so what I do is give them a 1/2 orange as it seems to get them into the mood if you will and I let them do the rest. Time is your best friend here........ . I would just keep them well fed and warm and it should happen on their own. Your juvies will need to molt into adult before they breed and I cant remember off hand if it takes a couple of weeks for dubias. Once they started they dont stop........ :lol:
Time is definitely your best friend! I won't lie... it will take a few months to get a self-sustaining colony going but its worth the wait IMO. The less you disturb them the faster they will breed once they get to adult size. They need a source of protein aswell so dry dog/cat biscuits are great... otherwise they'll start to eat the wings on the adult males instead! (I've learnt this the hard way as you can tell by the amount of scratty winged males i've got in the tub lol). They need a level of humidity to help them to shed too. I've been spraying the sides if the tub every night and that seems to be working ok so far.
I've been giving mine navel oranges (roach viagra lol) and water crystals for a water source, tropical fish flakes and ground up cat food then a bit of whatever i feed my beardies too.
It can take a few months for them to reach adult size, and then once a female is pregnant, it takes her a month to give birth. Protein helps them grow, so you probably want to start giving them either ground up cat/dog food or tropical fish flakes (my roaches love fish food, and it's high in protein and doesn't need to be ground up). You actually don't want to keep them somewhere "dry," since they are tropical roaches and native to hot, humid climates. As MarleyMoe suggested, you can spray water on the sides of the tub, but make sure it doesn't get the dry food or the egg crates wet, or you might end up with a mold problem. Keeping a full dish of water gels in the bin with them will help with humidity as well. If the humidity is too low, the roaches won't be able to molt, and they'll die.
It can take a few months for them to reach adult size, and then once a female is pregnant, it takes her a month to give birth. Protein helps them grow, so you probably want to start giving them either ground up cat/dog food or tropical fish flakes (my roaches love fish food, and it's high in protein and doesn't need to be ground up). You actually don't want to keep them somewhere "dry," since they are tropical roaches and native to hot, humid climates. As MarleyMoe suggested, you can spray water on the sides of the tub, but make sure it doesn't get the dry food or the egg crates wet, or you might end up with a mold problem. Keeping a full dish of water gels in the bin with them will help with humidity as well. If the humidity is too low, the roaches won't be able to molt, and they'll die.