https://dubiaroachdepot.com/guidance...troubleshooter

I've found this to be helpful. Maybe other people will too.

My dubias are still not producing nymphs, but at least they're breeding, as an aborted oothacae I found proves.

My box has been at the correct temperature for several months (though it might have gotten too low several times). The humidity is high. I feed the roaches dubia chow, lettuce and carrots.
Here's what I think may be wrong:

1.Stress: I've moved the box around too frequently or the bugs arrived stressed.
2. Too many males. Do I just kill some of them? Seems a little wasteful, but if they're eating nymphs...
I'm going to divide my colony up and see if that helps.
3. Not enough frass. Maybe I've been cleaning out the box too well.

If anyone wants to make a suggestion, please do.