Although I hate to do it, (I'm a nature take it's course kinda girl) I have found that the predatory wasps in my area are so rampant that I had to screen my last batch in. But yes, if you are growing them in an enclosure already, just placing them on their food source and making sure there is enough of it should do well. Others with more experience will surely give their notes as well :)

I grow mine in a 5 gal aquarium covered with a cloth to keep out the predators.