1) Buy some water crystals ( tiny crystals that will expand when you add water)
2) Add water to a teaspoon of crystals in a cup
3) they will absorb the water and expand
4) once they are done expanding they are ready for your insects.
Note a 1lb bag of crystals will make a ton of water crystals that will probably last a while.
With a couple of teaspoons of the crystals which is not that much i was able to make about a gallon of water crystals. I only used about maybe 10% of the crystals shipped in the 1lb bag to make them.