F. H. KRECKER. 



about twenty-four to thirty inches. When individuals enter 

 this optimum zone they alight, if a surface is available, and orient 

 themselves in such a way that the body is parallel with a radius 

 projecting from the light. After alighting the insects usually 

 remain at rest, although there may be a certain amount of 

 crawling toward a position nearer the center. This is more often 

 done by those nearer the outer limits of the zone. When the 

 insects are numerous they become arranged in rows consisting 

 of individuals either directly behind one another or slightly to 

 one side and they thus form a striking pattern of radiating lines. 



-;-vV;-', 



^ s \ i 

 ^ \ 



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FIG. i. 



The accompanying figures illustrate the positions assumed with 

 regard to lights in different positions and combinations. 



The first figure illustrates the position assumed when the 

 surface extends about a light in all directions whether the plane 

 be horizontal or vertical. When any portion of the surface is 

 absent the pattern is of course interrupted to a corresponding 

 extent. The clear zone immediately surrounding the light was 

 approximately six inches wide. I shall call it the excitement 

 zone. Individuals that entered this zone became greatly 

 excited and fluttered about the light in a confused state. There 

 was no evidence to show that individuals at rest deliberately 

 entered the excitement- zone. Those immediately bordering on 

 it were rather restless and occasionally in crawling about some 

 were pushed into it and others on taking wing came within the 

 influence of the light. 



