I. Introduction 1 Historical 2 Methods 4 Future work 5 Illustrations 7 II. Species of cockroaches 7 III. Ecological relationships 14 Cave habitats 16 Cavernicolous cockroaches 17 Cockroaches from burrows 23 Desert habitats 25 Desert cockroaches 27 Aquatic habitats 30 Amphibious cockroaches 31 Outdoor habitats 33 Cockroaches from outdoor habitats 35 Structural habitats 70 Land-based structures 73 Cockroaches associated with land-based structures 74 Ships 82 Cockroaches associated with ships 85 Aircraft 87 Cockroaches associated with aircraft 88 IV. Classification of the associations 91 V. Mutualism 96 Bacteroids 96 Cockroaches in which bacteroids have been found 99 Bacteria 100 Protozoa 101 VI. Viruses associated with cockroaches 103 VII. Bacteria associated with cockroaches 104 VIII. Fungi and yeasts 127 Fungi associated with cockroaches 129 IX. Higher plants associated with cockroaches 139 Damage to plants by cockroaches 162 X. Protozoa associated with cockroaches 166 XI. Helminths associated with cockroaches 190 Helminths for which cockroaches serve as primary hosts 192 Helminths for which cockroaches serve as intermediate hosts 203 Helminths whose eggs have been carried by cockroaches 208