402 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1955 



journey. Eepelled by bright light, she never leaves the bivouac in 

 the daytime, but is drawn fi-om the cluster in the course of the nightly 

 exodus and must then rmi the distance with a thick entourage of work- 

 ers obstructing her variously in the frenzy of their excited activities. 

 Throughout the nomadic phase the queen lays no eggs, and is in the 

 condition shown in plate 2, upper, with contracted gaster. Tough 

 exoskeletal armour plates, now overlapped closely, protect the vital 

 part of her abdomen, and her powerful legs carry her over the most 

 uneven paths, easily overcoming physical impedances in the difficult 

 route despite being trammeled by her pellmell retinue of workers. 



Wlien the queen reaches one of the periodic climaxes in her existence 

 and is delivering the enormous mass of eggs that she then produces, 

 her gaster is so greatly distended with maturing eggs that the exo- 

 skeletal plates are forced far apart and the intersegmental membranes 

 are tightly stretched between segments. Her gaster then may become 

 22 mm. or more in length (equal to her total body length in the con- 

 tracted condition) and very bulky. Although the tightly stretched 

 membranes of her gaster are very tough and tests show that tlie queen 

 is able to walk about even when physogastric, carrying ^vorkers, un- 

 doubtedly a long run in an emigi-ation would prove to be a great risk. 

 But at such times, when the queen's condition makes her exceedingly 

 vulnerable to jarring or abrasions, the colony is passing through a 

 statary phase and no emigrations occur. The queen then remains at 

 the center of a quiescent mass and has at least a week for undisturbed 

 recuperation in the bivouac after the eggs have been delivered. This 

 is all the more remarkable because it is an indirect outcome of her own 

 rhythmic physiological processes. 



Although most of the workers must have relatively short lives, our 

 studies on Barro Colorado show that the normal function of a colony 

 queen may be a long one. We have been able to keep queens on record 

 by marking them permanently in a distinctive manner. With iridec- 

 tomy scissors, one or two minute triangles of cuticle are cut from the 

 edge of abdominal sclerites. The cut edges soon darken, so that the 

 queens can be recognized readily when they are removed from their 

 colony. Many recoveries have been made after several months, and a 

 few after one year. The longest record thus far is that of a hauiatum 

 queen (colony '48 H-15), marked on December 23, 1947, and reidenti- 

 fied by means of her unique mark on April 3, 1952, nearly 5 years 

 later. She was in vigorous condition and carrying out a normal re- 

 productive function late in May 1952, when her colony was last seen. 

 This queen therefore had a functional life of at least 4i^ years, in 

 which an estimated total of 45 broods (probably more than 1,800,000 

 individuals) had been produced. In 45 nomadic phases, with 16 emi- 

 grations each on the average, it is estimated that her colony traveled 



