82 
Psyche 
[June 
mm across their short diameter and 17 — 30 mm across their long, 
averaging 19.8 X 22.9 mm ( 1 1 ) . 
At one location (Brunswick, Ga.), I repeatedly noted a curious 
activity by eight of the 18 beetles observed. It occurred during the 
shaping process and involved rapidly rotating the ball in the sand, in 
a stationary position, for about two minutes with the result that the 
ball became coated with sand. As the ball acquires a sand coat on 
being rolled anyway, this observation cannot yet be explained. 
Rolling . Once shaped, the ball is quickly rolled in a direction away 
from the dropping. Rolling is performed with the beetle head- 
downward behind the ball, pushing backward against the ground 
with the forelegs and steadying the ball with the middle and hind legs. 
The middle legs alternate between the ground and the ball and the 
hind legs are always in contact with the ball, alternately pushing 
against its surface with walking movements. When an obstacle is 
encountered the beetle will always attempt to push the ball over it 
rather than go around it (fig. 5). Frequent falls and tumbles occur, 
as a result of which the beetle may temporarily lose the ball. If this 
happens, the ball is searched for on foot in random patterns by the 
beetle, antennae outstretched. The procedure before resuming rolling 
after a tumble is always the same: the beetle climbs on top of the 
ball and turns so as to come down on the side of the ball necessary 
to resume rolling in the same direction in which it was rolling im- 
mediately before the tumble. Occasionally (2), the beetle will pause 
seemingly without reason, climb on the ball, turn around in either 
direction, and descend to resume rolling. 
Once started in a given direction, the beetle will continue in this 
direction about half the time (13 of 23), although the actual course 
followed is quite zig-zag at best. The rest of the time there are 
pronounced changes in direction during rolling (enforced direction 
changes due to obstacles are not counted here). I have attempted 
to relate the direction in which a ball is first rolled away from the 
dropping to three possible environmental factors: the wind direction, 
the slope of the ground, and the position of the sun. In figures 6 — 10 
I have indicated by dots the initial directions taken in relation to 
each of these three factors in turn, according to 70 observations on 
both food and brood balls in all localities. The number of dots indicates 
the number of times a ball was seen rolled at a given angle (to the 
nearest 45°) from the position or direction of the environmental 
factor indicated. 
Chi-square calculations were made on each of the diagrams to 
