go Instinct and Intelligence 



wall, up which the wasp repeatedly made an 

 attempt to climb, but kept falling back. The 

 insect, failing to scale the wall, then ran round 

 the bottom of it until it reached an opening, 

 through which it crept into the yard. Then 

 crawling through the fence which separated the 

 two yards, it dropped the caterpillar near the 

 root of a tree and flew away. After a short 

 zigzag flight it alighted on a flower-bed in which 

 were two holes. The wasp soon left the bed 

 and flew back to the tree, stopping twice on 

 the road. It then landed on the caterpillar it 

 had left and dragged it into its hole, which it 

 covered with sand. 



As an example of instinctive processes in 

 insects we may refer to the slave-making ants 

 which are incapable of tending their young, and 

 even of feeding themselves. At a particular 

 period of the year, when the nests of the black 

 ants contain the neuter brood, at a given signal 

 made by certain of the leaders of a nest of red 

 ants, an army of these insects leave their nest 

 and advance in fairly straight lines, the van- 

 guard, which consists of eight or ten ants, con- 

 tinually falling back to the rear. In some cases 



