382 F. H. KRECKER. 



as to strike the insects on the side of the body. They were 

 resting on boards placed horizontally. A few of them flew 

 away but most of them eventually faced the current. Individuals 

 placed on a rough surface, such as a wire screen, which afforded 

 a better foothold frequently tried to walk away. When facing 

 the current of air an individual would raise its long, slender 

 front pair of legs and extend them forward and upward at an 

 angle of about 40 degrees. When held in this way the legs re- 

 semble antennae and it is possible they have a sensory function. 

 However, cutting them off had no apparent effect on the reactions 

 here in question. The time required for the turning reaction 

 varied from an almost instantaneous response to two minutes. 

 In the majority of cases the response was gradual and occupied 

 from 30 seconds to one minute. The rapidity of reaction de- 

 pended upon a correlation between the strength of the breeze 

 and the part of the body it struck. 



The influence of the area stimulated is shown in experiments 

 with the wings. The latter are large in proportion to the body 

 and meet over the back in a perpendicular position. They, 

 therefore, present quite a broad surface. When a current of 

 air of an intensity sufficient to blow the wings slightly to one 

 side was directed against them individuals would react in fifteen 

 to thirty seconds, whereas when this current was directed against 

 the thorax or the abdomen the response was slower, if indeed 

 any occurred. A stronger current directed against any of these 

 parts brought about a correspondingly more rapid reaction. 



In another series of experiments a current of air was directed 

 from the posterior lengthwise of the body along the dorsal 

 surface of a number of individuals. The response in these cir- 

 cumstances was also an eventual facing about to the current. 

 A current of air striking an individual longitudinally along the 

 mid-dorsal surface is neutral so far as lateral directions are con- 

 cerned. In the cases here in question the current blew the wings 

 to one side or the other and then as before the insects turned 

 around toward the side on which the strain was exerted. 



The experiments were repeated on a group of individuals from 

 which the wings had been removed. The results from a current 

 of air striking the insects on the side of the body were the same 



