reported that cannibalism was common in a laboratory colony of _Periplaneta brunnea_ and that egg capsules deposited by a female were often eaten by the other cockroaches. _Periplaneta americana_ occasionally ate other cockroaches and their oöthecae and also attacked members of their own species (Lederer, 1952). Griffiths and Tauber (1942) recorded the killing of male American cockroaches by females of the species: "One female was especially vicious and attacked each new male as he was introduced into the container. Most of such males had molted less than 2 days previously. Older males were more capable of defending themselves against attacks of these cannibalistic females." Even though adequate food may be present, females of _Periplaneta americana_ may eat their own eggs (Klein, 1933). Some females may regularly eat their oöthecae as soon as they are dropped (Griffiths and Tauber, 1942). To be completely eaten an oötheca generally must be attacked before it has hardened. If a hole is eaten in one side of the capsule, the cockroach may devour the eggs and leave a portion of the oötheca. Frequently only the keel or a part of the keel is eaten and when this occurs the eggs fail to hatch and usually do not complete development because of the rapid loss of water (Roth and Willis, 1955). When adults of _P. americana_ and _P. australasiae_ were deprived of food, both males and females ate newly deposited eggs and, finally, the females ate the males (Sonan, 1924). _Parcoblatta virginica_ in laboratory cultures also may eat part of its oöthecae; in this species only the soft end of the recently deposited oötheca was eaten (Roth, unpublished data, 1957). Cros (1942) observed oöthecae-bearing females of _Blatta orientalis_ attack and kill males of the same species which were attempting to mate; these males were then eaten by the females. Cros also observed injured and recently molted nymphs of _B. orientalis_ to be eaten by others of the same species. Pettit (1940) noted that cannibalism in his culture of _Blattella germanica_ occurred only when the insects were molting. Adult insects attacked the molting cockroaches more often than did the nymphs. However, nymphs after the fourth instar occasionally set upon other molting nymphs. First-to third-instar nymphs rarely victimized their mates. The victims were all older than third instar; the later stadia were progressively more subject to attack, and molting adults suffered the greatest mortality. No direct correlation was noted between population density and cannibalism. German cockroaches may attack newly molted nymphs of their own kind and cause them to deflate (Gould and Deay, 1938). Lhéritier (1951) has observed the hatching nymphs of _B. germanica_ being devoured by their congeners even before they have left the oötheca.