Colonies are a little slow to get up and running. I think I started with around 300 mixed and it took a few months to notice real growth in the size of the colony.

To keep them breeding, the temps should be maintained around 86 - 90 degrees - keep them fed and watered (also they like it dark). I use a coffee grinder to grind up cat food. They do not grow as fast as lobsters, but the other benefits of Dubias make up for the slower growth. Don't let them get too humid as mold will grow and that will kill off the colony. I keep the water crystals right under (4 - 5 inches) the ceramic heat lamp and it has been working great at maintaining some humidity, but not too much.

Heck, I've got so many I'm giving them away to friends now. They're starting their own colonies.