NOTES ON THE LIFE CYCLE AND 
MYRMECOPHILOUS ADAPTATIONS OF 
CREMASTOCHEILUS ARMATUS 
(COLEOPTERA: SCARABAEIDAE ) 
By Gary D. Alpert 1 and P. O. Ritcher 2 
Introduction 
Adult cetonine scarabs of the genus Cremastocheilus are known 
for their association with ant colonies (Wheeler, 1908). The genus 
consists of approximately 40 species and has been recorded only in 
North America north of the Isthmus of Tehuantepec (Howden, 
1971). Twenty- three species have been collected with 11 different 
genera of ants, yet their true relationship with the host ants remains 
unknown. Cazier and Statham (1962) and Cazier and Mortenson 
(1965) have summarized current knowledge of the genus based 
largely on their own studies of adult bionomics of several species 
from Arizona. The only information, however, on the development 
of the immature stages of this genus is a few scattered notes that 
the larvae of some species do occur in ant nests (Mann, 1911; 
Wheeler, 1908a; Windsor, 1964; and Ritcher, 1966). 
Th is is the first account of the life history and development of 
C. armatus Walker, a western species (Fig. 1) occurring with 
different species of Formica ants from British Columbia to California 
and Nevada (Potts, 1945). The major host ant, F. obscuripes 
Forel. is one of the most common mound building ants in western 
North America. A very pugnacious and aggressive ant, obscuripes 
builds large mounds of soil and vegetation containing 50,000 or more 
individuals (King and Walters, 1950). How armatus survives 
from egg to adult w'thin these nests was the object of field and 
laboratory studies. 
Methods 
The following account is a synthesis of results obtained in western 
and central Oregon from 1957 to 1961 and eastern and western 
Washington from 1970 to 1975. All four study areas were charac- 
1 Museum of Comparative Zoology, Harvard University, Cambridge, 
Massachusetts 02138. 
department of Entomology, Oregon State University, Corvallis, Oregon 
97331. 
Manuscript received by the editor December 29, 1975. 
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