106 
Psyche 
[June-September 
ously increasing. Buzzing runs ( Schwirrlaufen ) performed by some 
scouts at the nest site apparently triggered this retreat, since their 
occurence coincided with the start of the scouts departures (see Fig. 
1). Moreover, buzzing runs have been observed in two other con¬ 
texts involved in swarming—when a swarm first leaves its nest, and 
later when a swarm lifts off from its interim cluster site; and in both 
cases the buzzing runs seem to signal “Let’s go!” (Lindauer 1955, 
Martin 1963). 
We counted all buzzing runs performed on the outside of the 
nestbox during each interval, but probably the majority were per¬ 
formed inside. The behavior of the buzz runners ( Schwirrlauferin) 
we observed matched the descriptions of Lindauer (1955), Martin 
(1963), and Esch (1967) for buzz runners observed during nest 
departure and swarm lift-off. They made excited zig-zag runs over 
V) 
IT 
< -I 
MINUTES BEFORE LIFT-OFF OF SWARM 
Fig. 1. Mean over 5 min interval of counts each 30 sec of the number of bees 
visible on the nestbox (open bars, left scale), total number of buzzing runs observed 
on the nestbox during 5 min interval (solid bars, near right scale), and number of 
blue-marked scouts visible on the swarm cluster at various times (solid line, far right 
scale) as time of swarm flight approached. Vertical bars denote plus and minus one 
standard error. Counts document the return of the scouts from the nest site to the 
swarm cluster in preparation for the swarm’s flight to the nest site. Buzzing runs at 
the nestsite apparently trigger the scouts’ return. 
