_Nauphoeta cinerea_ in laboratory cultures will eat newly hatched young of the same species (Roth and Willis, 1954; Willis et al., 1958). In Hawaii, in nature, _N. cinerea_ may kill and eat the cypress cockroach, _Diploptera punctata_ (Illingworth, 1942; Fullaway and Krauss, 1945). Bunting (1956) stated that species of _Neoblattella_ are omnivorous with carnivorous and cannibalistic tendencies. An adult female _Panchlora_ sp. was killed and eaten by _Neoblattella_ sp. in captivity. A male, provisionally identified as _N. celeripes_, was killed and partly eaten by two other males of the same species. The factors influencing the extent of cannibalism among cockroaches are not completely known. According to Wille (1920) hunger was not the cause of cannibalism in _Blattella germanica_. Wille claimed that the tendency toward cannibalism increased at high temperatures and decreased at low temperatures. Pettit (1940) also noted this effect. Gould and Deay (1938) stated that under crowded laboratory conditions, when there was a scarcity of food, cannibalism among _Periplaneta americana_ was common. The injured cockroaches and those unable to molt were often eaten. Adair (1923) made similar observations. Undoubtedly, conditions of crowding, availability of food, temperature and other factors all influence cannibalism, but practically no experimental work has been done on this subject. It is interesting, in comparison with the above positive examples of cannibalism, that both Saupe (1928) and Roeser (1940) observed no cannibalism during extensive studies with _Pycnoscelus surinamensis_. In fact, Roeser stated that there was never a case of cannibalism in spite of long hunger periods imposed on both nymphal and adult insects. XVII. ASSOCIATIONS AMONG COCKROACHES Besides preying on their own species or on other blattids, cockroaches exhibit additional symbiotic relationships among themselves. These relationships are (1) the familial associations of parent and offspring, (2) gregariousness, (3) intraspecies fighting, (4) interspecies compatibility, and (5) interspecies antagonism. There are some inconsistencies between observations made on the same species by different workers, which only further observation and experimentation will explain. Some of the reported observations are unique; this is especially true for the feral species. Because of the paucity of information, it is impossible at this time to make valid generalizations about some of these interesting relationships. FAMILIAL ASSOCIATIONS The females of many species of cockroaches insure varying degrees of protection to the developing young in their ways of disposing of the oötheca after it has been formed. The extent of this association between the mother and her developing progeny varies from the minimum amount of time spent by oviparous females in concealing their oöthecae, to the duration of embryogenesis in the so-called viviparous species, a period of over a month or more.