398 ANlSrCJAL REPORT SMITHSONIAN INSTITUTION, 1955 



On the other hand, at the beginning of the study there was a precise 

 coincidence between the emergence of a callow brood and the begin- 

 ning of a nomadic phase of maximal activity and regular emigration; 

 later the maturation and enclosure of a larval brood coincided with 

 the passing of the colony into a statary phase of minimal raiding and 

 no emigration; finally the colony entered a further nomadic phase 

 when the latter brood emerged as callow workers. On the last day 

 at the second statary site, circumstances were closely equivalent to 

 those at the site vacated when the study began. On this day the 

 colony staged a large 3-system raid, the mature pupal brood was re- 

 leased from cocoons, and the colony moved to a new site at the day's 

 end. On the second emigration of this new phase, it was discovered 

 that the colony had a new brood of very young worker larvae. It had 

 come full circle in just 37 days after leaving the first site. 



This coincidence of events in colony behavior and brood condition 

 has been established as the rule not only for E. hamatwm and hur- 

 ckeUi, but also for related species. Surprisingly enough, the de- 

 scribed nomadic-statary cycle occurs tliroughout the year, in both 

 rainy and dry seasons, with an unbroken succession of overlapping 

 broods and correlated activity cycles. This was confirmed by studies 

 of 31 hamatu77h colonies and 19 hurchelli colonies for various lengths 

 of time in the dry season and early rainy season of 1946 (Schneirla, 

 1949) and of comparable series in these species for various lengths 

 of time in a study extending from the late rainy season of 1947 

 through most of the dry season of 1948 (Schneirla and Brown, 1950). 

 Colony '46 H-B of E. hamatum^ while on record from February 12 to 

 June 5, 1946, completed three full nomad-statary cycles and began a 

 fourth (see fig. 4), as follows: Cycle 1, nomadic 16 days, statary 21 

 days, total, 37 days ; cycle 2, nomadic 17 days, statary 20 days, total, 

 37 days; cycle 3, nomadic 16 days, statary 20 days, total, 36 days. 

 This study ended after a further series of four nomadic days. In 

 the course of the 49 observed emigrations in these three complete 

 cycles, the colony moved from the area north of Barbour trail to the 

 area of Gigante Point on the opposite side of the Island, an overland 

 distance of 2 miles, and a total distance of somewhat more than 5 

 miles traveled in the successive emigrations. Throughout this entire 

 time the correspondence of changes in colony activities and brood con- 

 dition was exactly as we have described it for the colony studied in 

 1936. There was only a secondary difference in the duration of the 

 phases, which in hainatum are most frequently 17 days in the nomadic 

 phase and 20 days in tlie statary. E. hurchelli is somewhat more vari- 

 able in its nomadic phase, varying from 11 to 15 days. The statary 

 phase of this species is less variable than the nomadic, with a mode 

 of 21 days. 



