BIOTIC ASSOCIATIONS OF COCKROACHES — ROTH & WILLIS 2)Z7 



itself was killed. Lederer (1952) also made similar but less extensive 

 observations on fighting in this species, 



Pettit (1940) quoted Woodruff as stating that nymphs of Blattella 

 germanica, apparently healthy and perfectly normal, would do battle 

 for no apparent cause other than a chance meeting, and that occasion- 

 ally the fight was to the finish, the loser being eaten. Pettit could not 

 substantiate such voracious attacks, although he saw nymphs engage 

 in fights lasting about two seconds during which one would be driven 

 off by vigorous bites on legs or cerci. Small nymphs of B. germanica 

 tended to ignore each other, but third- and later-instar nymphs would 

 engage in "quarrels" of short duration when two met. Pettit noted 

 that males oi B. germanica that were crowded together quickly set 

 upon, but did not always kill, other cockroaches introduced into their 

 cage. When he isolated a dozen males in a small cage, they became 

 quarrelsome and three of the group were killed and partly eaten. 

 After several days the surviving males had taken positions so that each 

 was equidistant from his neighbors. Some of these males attacked 

 other males and a female that were introduced, by biting their legs 

 and cerci. Females under similar conditions were much less aggressive, 

 although Pettit saw some females that roved about biting all large 

 members of the group that were within easy reach. 



We have frequently observed aggressive behavior between males of 

 Nauphoeta cincrea, which resulted in torn wings. The males would 

 wrestle with each other rolling over and over. 



INTERSPECIES COMPATIBILITY 



We agree in essence with Chopard (1938) who stated that it is im- 

 proper to speak of associations apropos of the ecological distribution 

 of Orthoptera. He continued that it is clearly evident that different 

 species of Orthoptera, which are found grouped on a territory more 

 or less narrowly limited, have no interdependence among them. Their 

 grouping results uniquely from almost similar reactions to the dif- 

 ferent factors which characterize this limited milieu. There is neither 

 interdependence nor interaction ; the grouping is a false biocoenose, 

 born under the action of the environment, and does not survive a 

 modification of this milieu. 



However, as there are numerous examples of mutual toleration be- 

 tween different species as well as examples of incompatibility, the sub- 

 ject has more than academic interest even if no true ecological 

 significance. On the other hand, further study may show that certain 

 of these associations are definitely ecological, particularly among the 



