1986] Peeters & Crewe — Male biology in Ophthalmopone 279 
Table 1. Size of the male population in nests excavated during January-April. 
Males were not present at other times of the year. 
Date of 
excavation 
Number of nests Number of males found in each nest 
excavated (together with number of adult workers) 
January 1981 
4 tt 
5(145), 0(84), 6(142), 10(227) 
January 1982 
1 
1 7(> 1 40) 
January 1983 
3 ft 
3(116), 9(222), 6(121) 
February 1982 
5 + 
7(20), 9(80), 19(168), 13(72), 12(124) 
March 1982 
2 + 
0(119), 0(77) 
April 1981 
3 + 
0(318), 0(75), 1(445) 
April 1983 
2 + 
0(106), 2(121) 
# from 2 colonies 
+ from same colony 
Evidence that males remain in their natal nests until they are 
physiologically ready to mate was adduced from the following 
observations. An adult male that was painted while being carried 
between two nests, remained inside the second nest for nine days 
before it left and flew off. Dissection of males collected during 
excavations revealed that there was little or no sperm in the vasa 
deferentia and ejaculatory ducts of many of them. 
After the initial dispersal flight, males alighted on the ground and 
appeared to search for nests haphazardly. They walked quickly with 
frequent changes of direction, and investigated little holes and 
depressions in the soil. They regularly climbed up short grass stems 
or low vegetation from which they flew off, often for only a short 
distance. This behavior was interspersed with ground searches. On a 
number of occasions, males were observed either landing very close 
to nest entrances, or walking straight towards occupied nests shortly 
after landing. Five marked males were observed outside one nest on 
two successive days, indicating that after locating a foreign nest, 
Behavior around the entrances of foreign nests 
During the period of their activity, males were observed waiting 
immobile outside nest entrances, either on the ground or on top of 
short grass stems. The working assumption was that such males did 
not originate from these nests, because they always flew away from 
their natal nests. Some nests frequently had many males in their 
vicinity, while other nearby nests seldom had any around them. 
Males usually investigated entrance holes with their antennae and 
hesitantly walked in; some ran out immediately afterwards. Individ- 
ual males were repeatedly evicted from nests by workers (in nests 
