In this chapter the relations of other arthropods to cockroaches are either as parasites or as predators. Certain cockroaches have turned the tables on their adversaries and become predators themselves. This aspect of cockroach behavior is discussed in chapter XVI. Other associations of cockroaches, as commensals with other insects and as associates of other cockroaches, are discussed in chapters XV and XVII. Order ORTHOPTERA Family MANTIDAE =Hierodula tenuidentata= (Saussure) (?) (Serville) (Pl. 32) _Experimental prey._--_Blatta orientalis_, _Diploptera punctata_, _Eurycotis floridana_, _Leucophaea maderae_, _Nauphoeta cinerea_, _Neostylopgya rhombifolia_, and _Periplaneta americana_, U.S.A. (Rilling, personal communication, 1957): Mrs. Rilling wrote us that with the exception of _N. rhombifolia_, all the above cockroaches were readily eaten. All the mantids initially rejected _N. rhombifolia_ after grasping and making a brief attempt to chew the cockroaches. However, if specimens of _N. rhombifolia_ were left in the jars with the mantids, the cockroaches were usually eaten within the next 24 hours. _N. rhombifolia_ ejects an odorous substance when seized and the mantids probably ate these insects after most of this secretion had been depleted. It is highly probable that the secretion of _N. rhombifolia_ may deter the mantid's attack, but it should be pointed out that, with the possible exception of _N. cinerea_, all the other species fed to these mantids give off odorous substances when seized or disturbed. Apparently, certain naturally repellent compounds will deter this mantid, whereas others that are presumed to be repellent will not; however, the nutritional state of the mantid is undoubtedly a factor which may limit the effectiveness of certain repellent secretions against this predator. _Byrsotria fumigata_, teneral males, and _Periplaneta australasiae_, nymphs, U.S.A. (Roth and Willis, unpublished data, 1958). _Diploptera punctata_, U.S.A. (Eisner, 1958). =Mantis religiosa= Linnaeus _Common name._--European mantis. _Experimental prey._--_Nauphoeta cinerea_, and _Periplaneta americana_, U.S.A. (Rilling, personal communication, 1957). =Metallyticus semiaeneus= Westwood _Experimental prey._--Cockroaches, Borneo (Shelford, 1916). =Sphodromantis viridus= (Forskål) _Synonymy._--_Sphodromantis bioculata_ Burmeister [Gurney, personal communication, 1958]. _Experimental prey._--_Blatta orientalis_, Egypt (Adair, 1923): This species of cockroach was apparently used regularly as food for the mantid in the laboratory. =Stagmomantis carolina= (Johansson) _Common name._--Carolina mantis.