My panther girls are about a year old. I dont feed the sticks often because I am still learning how to raise them. I lost most of my nymphs because as a winter feed I saved dried oak which they wont eat. Luckily, I had two nymphs live, grow and lay eggs before they died and there were still eggs hatching from my last adults (died over winter) when the wild rose started popping. Next year I will keep a wild rose under lights, keep dried rose and raspberry branches and keep rose and raspberry branches (in water) in the fridge and garage as long as possible to try to keep the life cycle going. I have Giant Vietnamese sticks. They dont eat Ivy. I am considering switching to a species that will but they are so much fun.
Chams love them. At one point, all I had available were dubias and it was going to take several days to get more bugs when one cham decided she didnt like dubias anymore. I fed sticks for two days and she started eating dubias again. I soon had other bugs arrive in the mail.
They are harder to feed in mass. I have to capture one or two at a time with a cup, pour them into another cup (they cling for dear life) put the lid on the second and repeat. Then I take the cup up to the chams and open the lid and just put the whole cup in there.
The eggs take months to hatch so even if you think you lost your entire culture, just wait and see if eggs continue to hatch.
Growing and breeding mantids is very hard. Hatching mantis oothes is easy.