I successfully used a console humidifier in my bug room and believe it greatly helped manage and fend off mismolt problems. I usually kept it between 70 and 80% humidity, if I remember right, in there and rarely had mismolts. In conjunction with a couple of heat lamps and space heater (in the winter) and closing off the AC vents in the summer, it kept the room toasty and moist, on the verge of sweltering at times... but great, in general, for mantis and feeders (fruit flies, house and bluebottle flies, crickets, roaches) ooth hatching, and accelerated growth. I also frequently misted net cages and containers. I recommend a humidifier as it worked well for me; but I don't think it's critical to successfully raise mantids. Misting frequently can be a low-cost, albeit more time-intensive, alternative. Best of luck in how you choose to add humidity!
