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Psyche 
[June-September 
thus about 3 m above the earth’s surface. The bees were dispersed 
throughout the swarm cloud; although density increased toward the 
center, there was no tight central cluster. 
Even though the two swarm flights observed on Appledore Island 
involved relatively short distances (350 m and 580 m) the maximum 
flight speeds stated above may be representative for swarms making 
much longer flights. The Dyce Lab swarm, which flew more than 
2000 m to its nest site, flew between stakes 435 and 605 m from its 
cluster site with an average velocity of 11.1 km/h. Beyond the 605 m 
point a fence and a field of brush prevented us from keeping even 
with the swarm, and so further velocity measurements could not be 
made. However, we feel that beyond the 605 m point the swarm 
increased its velocity little, if at all. 
One riddle about swarm flight is the mechanism whereby scouts 
direct the other swarm bees toward the nest site. Lindauer (1955) 
observed bees streaking through a swarm in the direction of the nest 
site, and has suggested that these streaker bees are the swarm’s 
scouts pointing the way. We have repeated Lindauer’s observation 
of streakers; a small proportion of the bees in the swarm were 
moving rapidly in a direction generally oriented toward the nest site, 
amidst the slower, more wavering flight of their sisters. Avitabile 
and his coworkers (1975) suggested another mechanism of swarm 
guidance: scouts somehow lead swarms by releasing Nasanov 
pheromone. They report leading airborne swarms along zig-zag 
pathways, though in the general direction they would fly anyway, 
using an artificial mixture of the Nasanov secretion. One problem 
with their experiment is that they may have been providing the 
orientation signal used by swarms at the very end of their flights (see 
below), and so have influenced the swarms’ flight patterns, but with¬ 
out duplicating the principal guidance system of swarms. This could 
be checked for by testing the orientation ability of a swarm whose 
members have had their Nasanov glands sealed shut with shellac. 
The island swarm ended its two flights with quite elegant braking 
so that in both cases the swarm’s center stopped within 10 m of the 
nest sites. The velocity plot in Fig. 2 (upper plot) indicates that the 
braking began at least 80 m before reaching the nest site. However, 
the mechanism of this braking, like that of the directional guidance, 
remains a mystery. 
4. Entry in the Nest Cavity 
Within seconds of the swarm cloud’s stopping near the nest site, 
