184 
Psyche 
[March 
Figure 1. Portion of a laboratory colony of Camponotus ( Colobopsis ) 
fraxinicola housed in a glass tube. The large soldiers use their cylindrical 
heads to block the circular nest entrances, which are cut by the minor 
workers. This colony has been fed ad libitum, and consequently both soldiers 
and minor workers are in replete condition. In the center, a soldier and 
minor worker exchange food by regurgitation. 
When twigs containing fraxinicola colonies are first broken open, 
both minor workers and soldiers rush out. Many attack any accessible 
alien object, such as the observer’s hand or a bit of cloth offered to 
them, biting it and spraying it with formic acid. The same response 
was obtained in the laboratory by permitting fire ant workers ( Sol - 
enopsis invicta) to invade the nests. Individuals of both castes were 
about equally aggressive and effective in repelling these invaders. On 
the other hand, the total population of minor workers, by virtue of 
its greater size, was more effective than that of the soldiers. 
To sum up the results, the fraxinicola soldiers are indeed a defen- 
sive caste, but their specialization makes them superior in only one 
aspect of this role. 
The Soldier as a Trophic Caste 
The fraxinicola major worker is also anatomically distinguished 
by its proportionately larger abdomen. All individuals dissected from 
two laboratory colonies had large fat bodies and well developed 
ovaries containing one to seven eggs, some of which were of very 
