110 
Psyche 
[June 
deal orientation in contrast to the usual feature of foraging col- 
umns confined under galleries or in narrow pheromone trails 
(Leuthold et al., 1976). In contrast to other termites, they have 
functional compound eyes and darkly pigmented body surface. 
Alate imagines and workers carry their own water supply in spe- 
cialized water sacs, according to Watson et al. (1971). We had the 
opportunity to observe carefully the pairing behavior of H. mos- 
sambicus on a single swarming day (9.4.1976) in Olorgesailie, 
Kenya. This study revealed an unusual modification also in the 
pattern of pairing behavior. The reproductive dispersal flight oc- 
curs during the hot period in the afternoon, often during full sun- 
shine on the day after a rainfall. The roles of male and female 
were found reversed relative to the behavior observed in other ter- 
mites. A mechanism of pheromonal sex attraction was clearly con- 
cluded from the behavior. Unfortunately, another flight during 
which we expected to carry out planned experimental analysis did 
not occur during our available observation time. 
Observations 
The climate of Olorgesailie, the area of observation in the great 
Rift Valley near Nairobi, is characterized by extensive dry periods 
and sporadic rainfall of 300-400 mm per year, concentrated in the 
months of February to May and to a lesser extent from October 
to November. Swarming of H. mossambicus in this area takes 
place after substantial rainfall following the main dry season (re- 
corded data of rainfall that released flight: 1.3 mm, 35 mm and 
21.2 mm). In this area the swarming often extends over several 
rains if the showers are only weak and sporadic. Swarming was 
recorded on (23.12.1971), 8.1.1973, 25.2.1973, (20.2.1974), 9.4.1976 
and 3.4. 1977. 3 The time of swarming recorded was always in the 
afternoon under sunny conditions on the day following rainfall. 
One expected flight did not occur with overcast sky and slight 
drizzle. 4 
3 Partly recorded by Mr. Kannugi, warden at the prehistoric site in Olorgesailie. 
The figures in parentheses are not well documented. 
4 Hewitt and Nel (1969) reported flight after a latency time of 4 to 6 days after the 
first substantial summer rains, in the Orange Free State in South Africa. They did 
not mention the meteorological conditions before and during flight. It seems worth- 
while to collect more data in both areas to decide whether the populations in the two 
zones of very different latitude (1.6°S and 29° S) behave differently in this respect. 
