62 INSECT BEHAVIOR 



repeated over and over, until at length she would come by chance 

 upon the brick supporting the object of her search. 



Different species of wasps vary greatly in degrees of accuracy in 

 rinding their nests. Some experience no difficulty whatever, others 

 have slight trouble, while still others spend at least one-third of their 

 nesting period searching for the elusive keyhole. So true is this 

 among solitary wasps that they might be divided into several groups 

 in the order of their respective accuracy. One group would contain 

 the wasps which build their nests in the ends of hollow reeds. The 

 home doorway may be in the midst of a dozen others, yet the owner 

 flies directly to her own threshold without an instant's hesitation. 

 The long black reed wasp l and the white-footed wasp 2 would be 

 shining examples of this enlightened group. Again we have such 

 wasps as the red-legged digger 3 who locates her tunnel in the ground 

 only after a series of circular flights in the air above it, much as a 

 carrier pigeon does upon release, before turning in the homeward 

 direction. In the third group, the one-banded dauber might head 

 the list of blunderers who find their cells only after a search, some- 

 times of great length, with the loss of much valuable time and energy. 



I do not believe that sight is an important factor to be considered 

 in any of the above cases. Most insects do not see such small objects 

 as their nests clearly from a distance. It is, to some extent, a sense 

 of smell, after the main journey has been accomplished, but they 

 rely chiefly on a sense of direction. Some have it more highly de- 

 veloped than others, just as the Indian finds his way in the forest un- 

 aided by compass, where another individual, a white man, would 

 fail or perhaps blunder through to his camp. The one-banded dauber 



flies accurately enough to her brick pillar, but lacks that balanced 



/ 



1 An unidentified species of Trypoxylon. 



2 Trypoxylon leucotrichium (Chap. IV). 

 8 A species of Sphex. 



