1975] 
Albert and Ritcher — Cremastocheilus armatus 
289 
ADULT 
PUPA 
3RD INSTAR- 
2 N D I N S T A R- 
1 ST INSTAR- 
EGG 
1 1 1 — I 1 1 
APR MAY JUN JUL AUG SEP 
Figure 5. Seasonal distribution of rhe developmental stages of Crema- 
stocheilus armatus collected from Formica obscuripes ant mounds. 
Predation 
During the spring adult beetles were predaceous on both ant 
larvae and pupae. In the field beetles were found feeding on larvae 
near the brood chamber while at the same time beetles in the outer 
galleries were motionless, suggesting that individuals moved into 
the center of the nest to feed and returned to the periphery when 
satiated. In the laboratory predation increased when beetles were 
deprived of food for over one month and when containers were 
darkened. It was not unusual for several beetles to feed on one 
ant larva at the same time. 
Unlike other scarabs, Cremastocheilus has an unusual cupshaped 
mentum which prevents ants from contacting the beetle’s mouth 
parts. When feeding, a beetle lowered its mentum and pierced an 
ant larva with its sharp maxillae. The mandibles are greatly reduced 
and aid in the transport of fluid. Feeding lasted from 10 to 30 
minutes as the beetle slowly pumped the ant larva dry. Beetles 
were not disrupted from feeding even when covered with attacking 
ants. 
