1988] 
Buschinger et al. — Chalepoxenus brunneus 
255 
Mating was directly observed four times in a flight-cage, on 11, 12 
and 15 June, 1987, hence about 2 weeks after the sexuals had 
hatched. The colonies were kept in a daily temperature rhythm of 
17/28°C with the temperature increase at 3 a.m. Sexual behavior 
was observed at 3 to 6 p.m., thus about 12 to 15 hours after the 
morning rise in temperature. 
The females did not exhibit any conspicuous behavior indicating 
a sexual calling or other stimulating actions. Males often made 
mating attempts already in the chambers of the formicaries, and one 
copulation was also seen there. Dealate females found in the formi- 
caries often proved inseminated when dissected. In one colony 1 1 
out of 12 dealate females were inseminated, only one had an empty 
receptacle. Such females, thus, could be used for colony foundation 
experiments. 
A sexual pheromone is present in the poison glands of C. muelle- 
rianus and C. kutteri. Pieces of filter paper soaked with the content 
of such a gland attract males and stimulate homosexual mounting 
attempts. The secretion is interspecifically active, and even cross- 
breeding of C.m. and C.k. was possible (Ehrhardt 1987). In order to 
check for a sexual pheromone in the poison glands of C. brunneus a 
few preliminary experiments were made. However, their number 
was restricted due to the small number of sexuals available, and the 
somewhat unexpected results certainly would deserve confirmation 
with more material. 
In repeated experiments the C. brunneus males failed to show any 
reaction to the poison gland content of their own females, and C. 
muellerianus males also were not stimulated by C.b. glandular 
secretion. Immediately after the test the same C.m. males showed 
the usual reaction to the sexual pheromone of conspecific females. 
When C. muellerianus poison gland secretion was presented to C. 
brunneus males, however, they were also attracted and stimulated 
and eventually engaged in homosexual contacts. Thus, C. brunneus 
has perhaps lost the ability to produce (much of) a sexual phero- 
mone, but the males have retained the capability to perceive the 
(similar or identical) pheromone of congeneric females. 
Colony foundation: 
When collected in the field, six out of 12 colonies (including the 
first one of Cagniant, 1985) contained one C. brunneus queen each, 
