1974] 
Wilson — Camponotus fraxinicola 
187 
mg, and the entire major population stored 54.59 mg. Thus although 
the majors made up a little less than 16 percent of the population and 
contained 28.43 percent of the wet weight in the non-replete condi- 
tion, they stored 38.15 percent of the liquid at repletion. 
A distinctive history of liquid flow unfolds when a colony dis- 
covers a single rich source of food and then endures a period of 
starvation — the circumstance simulated by the laboratory experi- 
ments. When the food is first discovered, the flow during the first 
one or two hours is from the foraging minor workers to other minors 
and majors encountered back at the nest. After saturation is attained, 
and 90 percent or more of the adults are replete, regurgitation con- 
tinues at a high rate. The two castes participate at about the same 
per- worker rate, with no apparent difference between the majors and 
minors in the frequency of donation as opposed to that of reception. 
Within 2-3 days after the food is cut off, majors have begun to feed 
minors larger quantities than they receive. Data on exchanges show 
that the major-to-major donations are fewer than would be expected 
by chance alone. This is due at least in part to the fact that the 
majors are relatively sluggish in their movements. The minors are 
much the more active caste, passing from one nestmate to another to 
collect and pass along the dwindling supply of liquid food. 
Acknowledgement 
This article is part of a continuing study on caste systems sup- 
ported by Grant Number GB-40247 from the National Science 
Foundation. 
Summary 
(1) The major worker, or “soldier,” of Camponotus ( Colobopsis ) 
fraxinicola , helps to defend the nest by blocking the entrance holes 
with its head, a behavior pattern reported by previous authors in 
other members of the genus. However, when the nest is breached and 
combat ensues, the soldier is no more aggressive or effective than the 
minor worker. 
(2) The nest entrances are constructed entirely by the minor 
workers, which cut them to fit the cylindrical heads of the majors. 
(3) Major workers respond to undecane, a general formicine 
alarm substance, by moving to block those nest entrances still open 
at the beginning of the episode. 
