78 
Psyche 
[June 
knowledge that the species feeds on cow dung in pastures, and my 
observations indicate that older dung is preferred. Decaying meat 
rarely attracts the beetles (Lindquist, 1935) and cadavers of small 
vertebrates may occasionally be made into balls and rolled off (Bragg, 
1 957 2 ) , as is commonly seen in some South American species of the 
genus (Luederwaldt, 1911). Human dung is readily taken, and 
many of the observations which follow are based on feeding behavior 
with human faeces. 
Miller (1954) analysed the role of 17 species of coprophagous 
scarabs in the dispersal of human faeces in the same general geo- 
graphical area in which this study was carried out. He found that 
C. pilularius made up 64% of the scarabs collected at human fecal 
traps in an open field in the daytime and that this species, because 
of its size, is potentially capable of removing more than 90% of the 
total exposed human dung removed by scarabs in the daytime, or 61% 
of the total at all times. This makes it by far the most important 
species of coprophage in this ecological situation (open fields). 
Tumble-bugs (Canthon, sensu lato) are not important in heavily 
overgrown situations, indicating the importance of the surrounding 
terrain. 
The recent very fine studies of Landin (1961) on the ecology of 
Aphodiinae finally prove for this group what has long been suspected 
by students of the coprophages in general, namely, that it generally 
makes no difference what kind of dung is eaten by a given species, 
but only where it is deposited, that is, to what extent it will be 
affected by heat and desiccation. If the type of dung is important 
(as for instance in the cases of cow and horse dung), it is because 
its consistency or shape may influence temperature changes and evap- 
oration rates (Landin, op. cit.). 
In C. pilularius activity is at the highest level in the spring and 
is very much dependent on rains, the most intense activity being seen 
immediately after showers. Activity usually begins at about 0900 on 
warm days (when the shade temperature reaches about 90°F by 1100) 
and terminates at about 1700. During dry spells the beetles remain 
continuously inside cow droppings under the crust and I have not 
seen them spending this time in the soil. No studies have been made 
regarding optimal temperature and humidity limits for this species. 
In the localities in which I observed this species the soil consisted 
2 Bragg’s observations on the rolling of decaying tadpoles were apparently 
made in central Oklahoma and therefore perhaps on the closely related 
Canthon imitator Brown. 
