Kim Taylor / American cockroach {Periplaneta americana} female carrying egg case.

Rod Williams / Question mark cockroaches (Therea olegrandjeani), captive

Paul Williams / Wingless cockroaches climb a tree stump to survive a wildfire, one is laying its eggs (ootheca) Western Australia, Australia.

Emanuele Biggi / Beetles (Omorgus costatus) and cockroaches, on guano pile with a dead swift chick. Deer Cave, Gunung Mulu National Park, Sarawak, Malaysia.

Emanuele Biggi / Dead swiftlet being eaten by darkling beetles and cockroaches. Deer cave, Gunung Mulu National Park, Borneo, Sarawak, Malaysia

Emanuele Biggi / Cockroaches (Periplaneta australasiae) on handrail, Gomantong caves, Borneo, Sabah, Malaysia.

Emanuele Biggi / Cockroaches (Periplaneta australasiae), Gomantong caves, Borneo, Sabah, Malaysia.

Emanuele Biggi / Cockroaches and darkling beetles feeding on a young dead Wrinkle-lipped free-tailed bat (Chaerephon plicatus). Gomantong caves, Borneo, Sabah, Malaysia.

Emanuele Biggi / Cockroaches and darkling beetles feeding on a young dead Wrinkle-lipped free-tailed bat (Chaerephon plicatus). Gomantong caves, Borneo, Sabah, Malaysia.

Emanuele Biggi / Cockroaches (Periplaneta australasiae) on wall of Gomantong caves, Borneo, Sabah, Malaysia.

Ingo Arndt / Madagascar hissing cockroach {Gromphadorhina portentosa} Africa

Christophe Courteau / Cockroaches (Periplaneta americana) on wall of Gomantong Cave. Sabah, Borneo. Malaysia.