Cockroach eggs look like small tan, brown or black capsules shaped something like a pill or a purse.
German and American cockroach eggs are approximately 1/3-inch (8 mm) long, while those of the Oriental and SmokyBrown cockroaches are slightly longer, reaching lengths of almost ½ inch (12 mm). Brown-banded cockroaches have smaller egg sacks less than ¼ inch (5 mm).
Roach eggs have a small ridge called a keel running down their length. This is a weak point in the case where nymphs emerge. When it’s time to leave the egg case, hatched nymphs swallow air to make themselves bigger. This causes the egg case to expand and break open along the keel, allowing the nymphs to escape.