Which feature is characteristic of female German cockroaches?

The characteristic feature of female German cockroaches is that they are usually darker in color with a more rounded abdomen. This distinctive physical trait helps differentiate them from the males, which tend to have a more elongated body shape. The rounded abdomen in females is not only a physical trait but also serves a functional purpose; it accommodates the egg case they carry, known as an ootheca.

This characteristic is important for pest control professionals, as it can aid in the identification of the species and understanding its reproductive habits. Recognizing the differences between male and female cockroaches is crucial for implementing effective control strategies, as females contribute directly to population growth when they carry and lay eggs.

In contrast, while the other options mention features such as the coloration and shape of the pronotum or the wings, they do not correctly pertain specifically to the females of the species, which is why they are not the best choices for this question.