Try to feed with drosophila.

The young should be fed on fruit flies (Drosophila sp.), aphids or other small insects. They do well if supplied with as much food as they can eat although they can last quite a while without food.

Many species are very aggressive towards each other and if kept in groups they will eat each other especially as one or two become slightly larger than their brothers and sisters. Some species will happily tackle prey as large as themselves.

As the grow they can be given larger prey, almost any insects will be eaten. Mantids do not usually need to drink. However if they are kept in a heated cage a small dish of water is a good idea in order to provide some humidity, alternatively the cage should be sprayed with water each day.

They live alone usually so its probably not a good to keep them together, they are veracious predators so if at all possible supply food constantly. Like he said, humidity is important to keep them healthy…uhhh i hope that helps a little. im not an authority on mantids but they are fascinating!