INTERRELATIONS OF INSECTS 301 



Origin of the Social Habit. Wheeler regards "trophallaxis," 

 meaning exchange of nourishment, as the source of the social habit in 

 wasps, ants, and termites; though admitting that the phenomenon has 

 not been observed in the social bees. He says: "If we confine our 

 attention largely to the ants, I believe it can be shown that trophallaxis, 

 originally developed as a mutual trophic relation between the mother 

 insect and her larval brood, has expanded with the growth of the 

 colony like an ever-widening vortex till it involves, first, all the adults 

 as well as the brood and therefore the entire colony; second, a great 

 number of species of alien insects that have managed to get a foothold 

 in the nest as scavengers, praedators or parasites (symphily); third, 

 alien social insects i.e., other species of ants (social parasitism);* 

 fourth, alien insects that live outside the nest and are " milked" by 

 the ants (trophobiosis) ; and, fifth, certain plants which are visited or 

 sometimes partly inhabited by the ants (phytophily)." 



