Egg cases are then generally placed on a surface in a hidden location. Egg cases are 3/8 inches long, brown, and purse shaped. Immature cockroaches emerge from egg cases in 6 to 8 weeks and require 6 to 12 months to mature. Adult cockroaches can live up to one year, during which females produce an average of 150 young. The amount of offspring in a cockroach egg depends greatly upon the species.     A female German cockroach carries an egg capsule containing around 40 eggs. Sh â¦ e drops the capsule prior to hatching. Development from eggs to adults takes 3-4 months.