418 TROPICAL WILD LIFE IN BRITISH GUIANA 



Different species of wasps vary greatly in degrees of 

 accuracy in rinding their nests. Some experience no diffi- 

 culty 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 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 in- 

 stant's hesitation. The long black reed-wasp and the white- 

 footed wasp would be shining examples of this enlightened 

 group. Again we have such wasps as the red-legged digger 

 who locates her tunnel in the ground only after a series of 

 circular flights in the air above it, much as a carrier pigeon 

 hovers when released, before turning homeward. In the 

 third group, the one-banded dauber might head a list of 

 blunderers who find their cells only after a search, sometimes 

 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. 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 developed than others, 

 just as the Indian finds his way in the forest unaided 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 sense of direction that lands the white- footed 

 wasp in a single flight at her doorway. 



In the wooden shutters of the Laboratory, I found fur- 

 ther evidence of the dauber's stupidity. For a nesting site, 

 she had selected in this case the narrow edge of a slat situated 

 midway between the top and bottom of the shutter. Below 



