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Psyche 
[Vol. 88 
O. versicolor has also returned to polyphagy along with poly- 
morphism, consistent with the general correlation seen in its tribe — 
the only higher dacetine to return secondarily to polymorphism, 
Strumigenys loriae , is also polyphagous (Brown and Wilson 1959). 
The degree of dietary specialization in the genus Orectognathus as a 
whole may have been overestimated: A colony of the monomorphic 
species O. clarki , collected by Holldobler in New South Wales, 
Australia, was maintained at a subsistance level on a diet of 
cockroach and mealworm fragments and honey- water (Holldobler, 
pers. comm.). However, this colony did not thrive, while the O. 
versicolor colony on the same diet flourished, raising many new 
workers and even males. Clearly O. versicolor does take non- 
collembolan prey more readily; what is not clear is the causality 
behind this correlation. The polyethism of Daceton, at least, is 
associated with predatory behavior. I had speculated that the O. 
versicolor majors might serve as “arthropod millers”, analogous to 
the seed-miller majors of Solenopsis geminata (Wilson 1978), their 
heavy mandibles used in processing a variety of prey with hard 
exoskeletons. Instead, they proved to be soldiers; perhaps in 
defending so efficiently, they somehow free smaller workers to 
forage for different prey items, which might require wandering 
further from the nest vicinity than would foraging for abundant 
collembolans. But this reasoning is vague at best and requires 
further investigation. 
It is the major caste and its role that make this species noteworthy, 
among dacetines and among ants in general. “Bouncing” is a new 
kind of nest defense strategy, ideally suited for repelling enemies in a 
species whose modified mandibles, designed for impaling soft- 
bodied prey, are of no use in fighting. Minors and medias can be 
seriously injured, in attacking invaders they are unable to harm. 
Bouncing minimizes contact between defenders and invaders, expel- 
ling the latter without a fight. Presumably, large workers of the 
monomorphic species ancestral to O. versicolor , modifying slightly 
the prey-capturing strike to pinch an extremity rather than pierce, 
found themselves able to shoot enemies away for short distances. 
This defense was so advantageous that heavier mandibles with 
blunt, pinching teeth were strongly selected for, along with guarding 
behavior, eventually producing the modern majors. Generally, 
major castes in ants serve as soldiers. In a few species, they specialize 
in physically blocking the nest opening with their large heads 
