324 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I4I 



German cockroaches may attack newly molted nymphs of their 

 own kind and cause them to deflate (Gould and Deay, 1938). Lheri- 

 tier (1951) has observed the hatching nymphs of B. germanica being 

 devoured by their congeners even before they have left the ootheca. 



Nauphoefa 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, A'^. cinerea may kill and eat the cypress 

 cockroach, Diploptera punctata (Illingworth, 1942; Fullaway and 

 Krauss, 1945). 



Bunting (1956) stated that species of Neohlattella are omnivorous 

 with carnivorous and cannibalistic tendencies. An adult female 

 Panchlora sp. was killed and eaten by Neohlattella sp. in captivity. A 

 male, provisionally identified as A'^. celeripes, was killed and partly 

 eaten by two other males of the same species. 



The factors influencing the extent of cannibalism among cock- 

 roaches 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 efifect. 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 simi- 

 lar 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 Pycnoscelns surinamen- 

 sis. 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, cock- 

 roaches exhibit additional symbiotic relationships among themselves. 

 These relationships are ( i ) the familial associations of parent and 

 offspring, (2) gregariousness, (3) intraspecies fighting, (4) inter- 

 species compatibility, and (5) interspecies antagonism. There are 

 some inconsistencies between observations made on the same species 



