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THE AMERICAN NATURALIST [Vol. XLII 



idea. Bees of the parasitic genus Coelioxys when caught 

 in the net almost invariably fly downward at the first im- 

 pulse, being thus positively instead of negatively geo- 

 tropic. A reason for this adaptation can be suggested 

 from a knowledge of their habits. Graenicher 3 has re- 

 cently shown that Coelioxys enters the nests of other bees 

 to lay its eggs. Thus in the event of its discovery by the 

 rightful owner of the nest, it may drop to the ground with 

 much better chances for escape than it would otherwise 

 have. 



Tiger beetles of the genus Cicindela are active fliers, but 

 are more at home on the ground, consequently when cov- 

 ered by the net they never rise on the wing, but invariably 

 attempt to escape on the surface of the ground, which 

 they can readily do if the net does not fit very closely. 

 Their actions can thus be traced directly to an adaptation. 



From any unbiased review of such facts, I think it will 

 appear that we can not hope to make wholly satisfactory 

 progress along the line of interpreting insect behavior by 

 means of studying their responses to stimuli in the labora- 

 tory, unless this be done with careful reference to their 

 habits and behavior in nature, and in relation to the 

 various external factors of their environment. 



8 Bull. Wisconsin Nat. Hist. Soc, vol. 3, p. 162, 1905. 



