258 



A MICHIGAN SPIDERS AND THEIR SPINNING WORK. 



air being stronger there than close to the surface of the earth, and conse- 

 quently affording much better facility for flight. The presence of a delib- 

 erate and wise volition seems evident from the fact that the Lycosids are 

 ground spiders, and not found habitually in such positions as the above. 

 They had certainly mounted to the top of the fence with the settled pur- 

 pose of taking advantage of the stronger breeze and better " send off " 

 which the superior height afforded. 



At least, it was easily determined that such an advantage did ensue 



from elevation. I selected some of the 

 lower stalks of grass from which silken 

 streamers were fluttering quite lazily. 

 Close up to the stalk or blade I saw the 

 spider placed back downward clasping 

 the thread with its claws. Sometimes a 

 thickened conical or flattened piece of 

 silk marked this end of the line. When 

 these grass stalks were broken off and 

 lifted into the air the streamers fluttered 

 out briskly and were soon snapped off, 

 carrying the young araneads away with 

 them. These experiments showed that 

 the act of ascension is aided by eleva- 

 tion, both in these cases and in those 

 where the spider mounts directly from 

 the perch. 



The young Lycosids had generally 

 chosen the very tops of fence posts as 

 points of ascent, and fortunately this 

 site suited the observer's convenience as 

 much as the spider's, and I could there- 

 fore notice with comparative ease the 

 methods of the miniature balloonists. 

 The spider's first action was to turn its face in the direction from which 

 the wind was blowing. Then the abdomen was elevated to an angle of 

 about forty-five degrees, and at the same time the eight legs 

 were stiffened, thus pushing the body upward. In order to per- 

 mit this movement the claws were brought in somewhat, but not 

 beneath the body, so that when the legs were stiffened the body 

 stood high above the surface. From the spinnerets at the apex of the 

 abdomen a single thread or ray of threads was exuded, and rapidly drawn 

 out by the breeze until, by reason of its delicacy, it was lost to sight. 

 Four, five, even six or more feet of the lines would at times be in view. 

 Gradually the legs were inclined in the direction of the breeze, and the 

 joints straightened out. The foremost pair of legs sank almost to the 



FIG. 270. Attitude of aeronautic spider just 

 before taking flight. 



Posture 



Before 



Flight. 



