Question

I just moved into a new apartment and was horrified to find cockroach egg cases in the cabinet under the kitchen sink! The apartment manager said that these were old egg cases that should have been cleaned up by maintenance. He said that there used to be a cockroach infestation that has been eliminated and that the egg cases were old and would not hatch anyway. Is he right? I definitely don’t want to move into a place that already has cockroaches!

Answer

I don’t know whether he is right about the cockroach infestation having been eliminated, but he is probably right about the egg cases not hatching.

If the egg cases are from a German cockroach (which is by far the most common cockroach found in apartments), they have most likely either already hatched or are probably not viable. The German cockroach female is unusual in that she carries her egg case protruding from her abdomen for about 3 weeks, until just before it is ready to hatch. About 24 hours before hatching, she places it in a secure place. If she drops the egg case before it is ready to hatch, it usually dries out and the cockroach embryos do not complete development.

There are three possibilities:

• The egg cases have already hatched.
• The egg cases are no longer viable and will not hatch.
• The egg cases were very recently deposited by a cockroach and could hatch very shortly.

Unless you have seen cockroaches or other evidence of cockroaches, I would say (3) is not likely. Based on your information, you are most likely seeing old cockroach egg cases that hatched some time ago.

If you care to look closely at the egg cases, you can actually tell whether or not they have hatched. If the case has split open along a side seam, the cockroach nymphs have already emerged. If the egg case is not split open but has dents or depressions in it, it means the eggs or nymphs inside have dried out and hatching is unlikely. But if the egg case is not split and looks plump and full, it’s probably ready to hatch. Since each egg case contains a double row of embryos, you could expect about 32 baby roaches to hatch out. Let’s hope your manager is right!