152 
Psyche 
[October 
Later in the summer, an experiment was also carried out to 
test Perez’ (1889) theory, according to which the so-called bum- 
blebee trumpeters are netvly emerged individuals which are 
exercising their wing muscles. On August 14th, at 1.30 P. M., 
I removed the board which shaded the nest of a queenless colony 
of Bremus fervidus so that the nest-box was exposed to the sun. 
The result was as follows: At 1.34, a worker appeared on top of 
the nest, and after crawling about a few seconds, began to fan 
vigorously. By 1.36 two more workers were engaged in this 
work, and by 1.38, the number of ^ trumpeters” had increased to 
six. All of these ‘trumpeters”, as the hardened pollen lump on 
the thorax showed®, were old bees which had done considerable 
foraging. Bremus fervidus usually nests on the surface of the 
ground, and hence this experiment incidentally also shows that 
Hoffer (1882-83), von Buttel-Reepen (1903), and Sladen (1912) 
are wrong in assuming that only “subterranean” species have 
“trumpeters.” 
Summary and Conclusions . 
1. The so-called trumpeters in bumblebee colonies are bees 
which are engaged in ventilating the nest. 
2. This ventilation is brought about by a rapid vibration of the 
wings and may take place at any time during the day or night. 
3. Species which nest on the surface of the ground likewise 
make use of this method of ventilating their nests. 
4. Ventilation by fanning is also resorted to by small bumble- 
bee colonies. 
5. Perez’ theory, according to which the so-called trumpeters in 
bumblebee colonies are newly emerged individuals which 
are exercising their wing muscles, is not founded upon facts. 
Literature Cited. 
Bachmann, M. 1915. Biologische Beobachtungen an Hummeln. 
Mitteil. Miinch. Ent. Gessellsch., Vol. 6, pp. 71-112. 
1916. Beobachtungen vor dem Hummelnest. Ent. 
Zeitschr. Frankfurt a. M., Vol. 29, pp. 89-90, 93-94, 
98-99, 103-104; Vol. 30, pp. 1-3. 
6The source of these pollen lumps will be discussed in connection with another paper. 
