Associations of colonial cockroaches (e.g., _Cryptocercus_ spp.) may be truly familial or they may merely result from gregariousness. Newly hatched nymphs of species that carry their oöthecae until the eggs hatch cluster near the mother. This may be a response to the mother as such, a search for shelter beneath the nearest object (thigmotaxis? or negative phototaxis?), or there may well be yet another explanation. Tepper in 1893 stated that the native cockroaches of Australia are almost wholly carnivorous; little supporting evidence for this claim has been brought forward since that time. The apparent supersedure of one species of domiciliary cockroach by another may result from antagonism between different species, or it may result from more rapid breeding and more effective utilization of available food and space; but which? Several species of cockroaches are frequently found associated with certain plants (e.g., bromeliads and bananas); the ecological relations in these associations remain to be determined. Many of the obscure associations between cockroaches and other insects, spiders, birds, and burrowing animals have never been adequately defined. The factors influencing cannibalism have never been thoroughly investigated experimentally. These are only a few ideas for future work that have occurred to us during the preparation of this review. We hope that these suggestions as well as other questions that may occur to readers will stimulate further research in areas where it is obviously needed. ILLUSTRATIONS Unless otherwise credited, the illustrations were prepared from photographs taken by the authors. Except where otherwise stated, all photographs were taken of unposed living specimens. II. SPECIES OF COCKROACHES The cockroaches referred to in this paper are listed below. The currently accepted name for each species is given alphabetically by genus and species irrespective of its taxonomic affinities. Synonyms used by certain authors whose work we have quoted are given in brackets under the respective species; the synonymy is supported by the reference citation that follows each synonym. References to illustrations of certain species (e.g., _Blaberus craniifer_) that appear in the paper follow the names of the describers. _Agis orientalis_ Chopard _Aglaopteryx absimilis_ Gurney _diaphana_ (Fabricius) [_Ceratinoptera diaphana_ Fabricius; Rehn and Hebard (1927)] _facies_ (Walker) [_Aglaopteryx devia_ Rehn; Princis (1929). _A. diaphana_ (Fabricius) in records from Puerto Rico only; Rehn (1932b); Gurney (1937)] _gemma_ Hebard [In Florida records = _Ceratinoptera diaphana_ R. and H.; Hebard (1917)] _vegeta_ Rehn _ypsilon_ Princis _Allacta similis_ (Saussure) [_Phyllodromia obtusata_ Brunner; Zimmerman (1948)] _Alluaudellina cavernicola_ (Shelford) [_Alluaudella cavernicola_ Shelford; Chopard (1932)] _Amazonina emarginata_ Princis