They begin breeding at four months old. Crayfish mate belly-to-belly, after a claw-waving courtship ritual. Dark green eggs are laid in clutches of about 50, attached to the mother’s pleopods under the abdomen. They hatch in about 2 weeks, and the 3/16 inch baby crayfish drop off and scatter about a week later. The mother continues to eat while brooding, and won’t eat her kids as long as she has sufficient food. The babies eat newly hatched brine shrimp, flakes, pellets, etc. Soaked leaves from deciduous trees will provide hiding and climbing places, plus bugs, bacteria, and fungi that the babies can eat between feedings. If starved or overcrowded they will attack each other and tear off legs, but these will grow back as long as the crayfish can still get around and feed. The babies can grow up in the tank with the adults, or you can separate the mother before the eggs hatch and raise the babies in their own tank.
from:
http://www.petshrimp.com/articles/cpatzcuarensis.html