A. The size and shape of a cockroach egg case varies depending on which cockroach species you are talking about. But all of the common cockroaches have a brown, oval, leathery egg case which encloses from 12-48 individual eggs, depending on the species. The somewhat hardened outer cover of the egg case protects the eggs inside from water loss, predators, parasites, and often…insecticides.

The German cockroach, our most common indoor cockroach, has an egg case that is about 1/3 inch long and about half as wide. There are indentations visible on the outside of the light brown egg case that correspond to the location of the eggs inside. If you split the egg case open down the middle lengthwise, you would see that each half contains a row of eggs. In the German cockroach’s egg case, there are 30-48 eggs which hatch in anywhere from 16 to 35 days depending on temperature and humidity.

Unfortunately, you usually don’t see a German cockroach egg case until it has already hatched. That is because, unlike most other cockroaches, the German cockroach female protects her egg case by carrying it with her until just about 24 hours before it hatches. You may have seen a cockroach with an egg case protruding from the rear of her abdomen. Usually though she tends to stay hidden away in cracks and crevices while her egg case develops.

The hatching of hidden egg cases is one reason why pest control companies often have to retreat accounts with cockroaches. You can tell whether an egg case has already hatched by looking for a split along a side seam where the nymphs have pushed the case open and emerged. An empty egg case may look dented. When you find multiple empty egg cases along with cockroach feces, you know the infestation has been going on for some time