208 INTELLIGENCE IN INSECTS 



furiously hurrying to and fro. But if the colony is weak, 

 the same kick, which at other times calls forth an army, 

 will have the contrary effect. The ants which just before 

 were running about the surface disappear through the* en : 

 trances of the nest as if by magic, and deathlike quiet 

 succeeds. " 



Wagner in his valuable studies on the behavior of bumble 

 bees, has observed that the bees of well populated nests 

 are much more pugnacious than those from nests containing 

 few members. In regard to the household activities of 

 bumble bees Wagner remarks that "Wenn eine Hummel 

 allein mit der Ausbesserung des Nestes beschaftigt ist, so 

 erscheint ihre Tatigkeit, obwohl wie stets geschaftig, doch 

 wenig energisch und intensiv. Kaum hat sich jedoch der 

 ersten Hummel eine zweite angeschlossen, so nimmt bei 

 gleichen sonstigen Bedingungen die Energie der Arbeit zu 

 und wachst bei jedem neu hinzutretenden Mitarbeiter mit 

 voller Augenscheinlichkeit. Gans dieselbe Erscheinung habe 

 ich auch bei Grabwespen beobachtet." The "brooding" 

 of the cells, gathering food, and various other activities 

 increase in vigor with increase in numbers, so that the popula- 

 tion of the large nests seems larger and that of the small 

 nests smaller than it is in reality. 



The influence of numbers upon the industry and courage 

 of social insects has been adduced as a proof of a high degree 

 of intelligence. That a populous ant colony will make an 

 attack upon a neighboring nest, while a colony with few 

 members shows a disinclination for warfare, may give the 

 appearance of a conscious realization of strength and a 

 power of reflecting upon the probable issue of an encounter. 

 As Wagner has pointed out, the explanation of such pheno- 

 mena may lie in the effect upon the individual of various 

 stimuli caused by its associates. The ant or bee commonly 



