INTELLIGENCE IN INSECTS 209 



receives from other members of its community numerous 

 olfactory, tactile, and perhaps auditory stimulations to 

 which it instinctively responds. These stimulations pro- 

 duce a condition of general nervous irritability which 

 spurs the insects on to activity and makes them ready to 

 combine in an attack upon an enemy. Whether or not 

 similar effects, as Wagner contends, are produced hi solitary 

 insects and I am not convinced that they are, from the 

 evidence adduced it is undoubtedly true that social 

 insects are dependent upon the stimuli received from the 

 cooperation of others to a remarkable degree. The confusion 

 produced by the loss of a queen and the gradual languishing 

 of a swarm in which no queen can be supplied, show how 

 sensitive* are bees to changes in their social environment. 

 Among bees, ants and termites signs of anger by one in- 

 dividual may awaken the whole community to a high pitch 

 of excitement. Each individual then serves to arouse the 

 others, and the larger the community the greater the mass 

 effect. 



Closely associated in many cases with the influence of 

 numbers is the effect of imitation. The activities of insects 

 not only arouse the energies of their fellows, but they also 

 direct then* efforts and in this manner secure cooperation 

 toward a common end. Ants keep together in their forag- 

 ing expeditions and often follow the "scouts" which act 

 as leaders, guiding the expedition to the nest to be pillaged. 

 "In artificial nests/' says Wheeler, "one usually sees a 

 particular activity started by one or a few workers, which 

 have more initiative or respond more quickly to a change 

 of conditions than the great bulk of the colony. The move- 

 ments of such individuals attract the attention of others in 

 their immediate neighborhood and these forthwith proceed to 

 imitate their more alert companions. Then the activity 



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