I have both fake plants at times, and live plants, especially vines that grow in humid conditions and like the temps that are present for the mantids benefit. I raise some of my own vines and the one that seems to do the best for me is a leatherly leafed perenial and flowering vine called Hoya carnosa. This is in my Chameleon habitat. When I drip water into the vine's pot it splashes around to the benefit of moistening the substrate which is a mat of coco fiber. This benefits the insects that are living mostly under the mat, which are Dubia roaches and crickets, with a few superworms as well. These come up to eat the fruit I leave and the chameleon takes her turn at snagging one here and one there. All seems to be in balance. The crickets have had babies and so have the Dubias. The vine is growing and there is oxygen being made by it. It is not a closed system obviously but pretty well balanced. I still have to clean up the poop. For mantids a similar habitat can be made. Some people like the Pothos vine, others use Orchids, and I like also the Anthurium from SA. It is brightly colored when it is in season and it can take the humidity (prefers 90-100 %). A four inch potted Anthurium is about $5 at Home Depot. Just be sure with fake and live plants to wash off the residues and leave in the sun (indirect preferably except for fake plants) to oxidize for a day or so. Do not leave outside if you live in a cold climate, and not overnight at all. This will help get any systemic pesticides out of the system and as you replenish it's moisture needs with pure water, the plant will be fit for use with your feeders and mantids. This is from my little experience with Ornamental Horticulture, and my few classes in that subject at Cal Poly SLO in the seventies. Some things never change.
