Of _Blatta orientalis_ Marlatt (1915) stated "This species is notably gregarious in habit, individuals living together in colonies in the most amicable way, the small ones being allowed by the larger ones to sit on them, run over them, and nestle beneath them without any resentment being shown." Haber (1919) also observed that this species is often noticed "huddled together, the younger ones crawling over, around, and beneath the older ones." Wille (1920) observed that nymphs of _Blattella germanica_ remained almost constantly in groups during the first and second instars, but less so during the third instar. He believed that the aggregations of young occurred because they could occupy narrow crevices where the larger insects could not penetrate. At usual room temperatures the older nymphs and adults lived completely isolated, but at certain temperatures they gathered together in large, tightly pressed groups. _Supella supellectilium_ is said to be gregarious (Gould and Deay, 1940). The smaller nymphs aggregate in small groups in rearing containers, but the older ones remain separate from one another (Hafez and Afifi, 1956). _Leucophaea maderae_ is sociable and rarely found alone; in their favorite hiding places, hills of these cockroaches can be seen hanging together (Seín, 1923). Wolcott (1950) also stated that _L. maderae_ is gregarious. Annandale (1900) observed that in the "Siamese Malay States" large colonies of _Periplaneta australasiae_ conceal themselves in hollows of bamboo logs from which houses are built. Moulton (1912) stated that he was astonished at the large numbers of _P. australasiae_ and _Symploce cavernicola_ that he saw swarming on the sides of caves of Mt. Jibong, Borneo. Rehn and Hebard (1905) stated that in Key West, Fla., _Eurycotis floridana_ fairly swarmed under the coquina boulders in the woods, in groups of a dozen containing both young and adults; _Pycnoscelus surinamensis_ was very abundant in the same type of habitat. Caudell (1905) also found the young of _E. floridana_ with the mature individuals. Hebard (1917) in his discussion of _Lattiblattella rehni_ again mentioned finding frequent colonies of _E. floridana_ in Florida. He also found many specimens of _Blaberus craniifer_ under boards on the ground at Key West. He found _Parcoblatta lata_ numerous under bark of dead pine trees in Alabama. However, Dowdy (1955), in an ecological study of oak-hickory forest in Missouri, stated that "_Parcoblatta_ [sp.] were never recorded as being gregarious, in fact they were mostly solitary. However, in some cases two were found together." Yet Blatchley (1895) stated of _Parcoblatta pensylvanica_ that in the winter in Indiana "One cannot pull the loose bark from an old log without dislodging a colony of from ten to a hundred of the nymphs of various sizes." Males of _Parcoblatta virginica_ were said to be often gregarious beneath loose bark and under chunks and rubbish (Blatchley, 1920).