Sexing Blattella germanica Nymphs

Ventral View of Abdominal Tergites:
  1. male first instar nymph
  2. female first instar nymph
  3. female second instar nymph
  4. female third instar nymph
  5. female fourth instar nymph
  6. female sixth instar nymph
  7. male sixth instar nymph

In most cockroaches the female ventral terminal abdominal segments (VIII and IX) retreat into the abdomen during larval development while the male tergites remain visible and countable I to IX throughout development and into the adult stage. In Blattella do not confuse the notch in the female IX tergite with the cleft between the male and female paraprocts (P).

Source: Ross and Cochran (1960) Ann.Ent.Soc.Amer. 53: 550-1.