140 
Psyche 
[September 
ants had died it would have been logical to conclude that they had 
starved, but they did not die. On the contrary they seemed to be in 
better shape than when they had been feeding on honey in the Janet 
nests. While the ants were in the Janet nests they had been given 
pieces of live-oak leaves on the chance that they might secure some 
nutricious secretion from them. The ants were definitely attracted to 
the leaf fragments and stripped off the small, stellate hairs which occur 
on the petiole and the lower surface of the blade. In the leaf of 
Q. emoryi Torr., the species mainly used in this study 2 , the largest and 
most conspicuous stellate hairs are concentrated at the base of the 
blade where they form a dense, tangled mat at either side of the mid- 
rib. These matted hairs often shelter small mites and it was at first 
believed that the ants were stripping off the hairs to get at the mites. 
Further examination showed that this was untrue for, after removing 
the stellate hairs, the ants discarded both the hairs and the mites which 
were among them. This led to a series of efforts, all of which failed, 
to secure an extract from the hairs which would be acceptable to the 
ants. Instead of attracting the ants, such extracts usually repelled 
them. But this did not eliminate the possibility that the ants might 
somehow be securing food from the stellate hairs and their actions in 
the aquaria nests seemed to strengthen this possibility. 
The oak twigs in the aquaria were sealed into small jars of water 
and usually remained fresh for ten days or more. During this period 
the buds on many of the twigs would unfold and small, new leaves 
would be displayed. If the ants were securing food from the stellate 
hairs, it might be expected that the hairs of the young leaves would 
be particularly attractive. It was, therefore, a surprise to discover that 
the ants paid much less attention to the young leaves than they did 
to the old ones. Subsequent events provided an explanation for this 
behavior, but its significance was not appreciated when it was first 
observed. 
About March 8th choke-cherry trees near the laboratory began to 
leaf out and a day or two later willow bushes began to produce catkins. 
Twigs from these plants were substituted for the live-oak twigs in the 
aquaria largely, it must be confessed, as a desperation measure. As 
2 It may be objected that O. emoryi is unsuitable for this work since its 
range lies well to the west of that of texanus. Admittedly it would have been 
preferable to use the leaves of 0. virginiana , as most of the nests of texanus 
have been found in this oak. Although texanus could not nest in 0. emoryi 
under normal conditions, its western counterpart, Cryptocerus rokweri Wh. 
does so. On November 7, 1952, the writer took a small colony of roh<weri that 
was nesting in Q. emoryi at Pena Blanca Springs, Santa Cruz Co., Ariz. 
