1963] 
Alatthews — Behavior of Canthon 
91 
period from hatching to adulthood as 29 — 44 days in captivity. There 
is only one brood pear per nest. 
Discussion of Sun Orientation 
The observations presented above on the possible role of the posi- 
tion of the sun in guiding the direction of ball rolling merit some 
discussion in view of the considerable amount of experimental work 
done in Europe over the past ten years on this aspect of behavior in 
a geotrupine scarab, Geotrupes sylvaticus Panz. (see especially Geisler, 
1961). 
My observations above suggest that in the absence of stronger 
guiding stimuli Canthon tends to roll away from the dropping in a 
direction which is either directly toward or directly away from the 
position of the sun (i.e., at an angle of O 0 or 180°) (fig. 10). By 
extensive experimentation Geisler (1961) was able to demonstrate 
definite “preference angles” ( Vorzugswinkel) of travel in Geotrupes 
of 90°, 45 0 , and 0° angles from the position of the sun or the plane 
of oscillation of polarized light from the sky. Whether the prefer- 
ence angles are to the right or to the left of the sun depends on 
whether it is afternoon or before noon respectively. This is brought 
about by the use of the right eye in the morning and the left eye in 
the afternoon for orientation and makes east the preferred direction 
in the morning and west in the afternoon. The alternation of eye 
use and consequent complete reversal of preferred direction (bearing 
in mind the movement of the sun) enables the beetle to return in the 
afternoon to the place it left in the morning. Geotrupes , therefore, 
has a definite compass-true orienting ability — requiring an angle- 
true orientation plus a time sense (“built-in clock”). 
According to Wagner (1957), the sun plays an important part 
in orientation during ball rolling also, the beetles apparently using 
its position to maintain travel in a given direction, the most frequent 
direction being directly toward the sun. These observations were 
carried out in Mexico on “Geotrupinae” — however, this subfamily 
does not roll balls and it seems almost certain that a species of Canthon 
was involved. 
The Geotrupinae are neither ball rollers nor primarily dung 
beetles, but it is possible that the light-compass orientation seen in G. 
sylvaticus occurs also in Canthon and other ball rollers. The exact 
adaptive purpose of this orienting ability is not clear either in Geo- 
trupes or Canthon, but it will be remembered that after a tumble 
C. pilularius always climbs on top of the ball before resuming rolling. 
