Incazelo yesichazamazwi ethi "iphela elikhulu" iyinambuzane enkulu yohlelo lwe-Blattodea, ebonakala ngomzimba oyisicaba, izimpondo ezinde, namapheya amabili amaphiko, ezinye izinhlobo ezikhula zibe zinkulu ngokungavamile. "Iphela elikhulu" ngokuvamile libhekisela ohlotsheni lwephela elikhulu kunephela elivamile, njengephela laseMelika (Periplaneta americana) noma iphela lase-Australian giant burrowing (Macropanesthia rhinoceros).