248 C. H. TURNER. 



Observation soon informed me that each burrow was visited 

 by bees at approximately regular intervals. Some of the nest- 

 holes were visited by a bee about once in twenty minutes, other 

 nests were visited more frequently. I soon discovered that where 

 each interval between the visits was much less than twenty min- 

 utes, two or more bees occupied the burrow in common ;^ but 

 that where the interval was twenty minutes or more, then only 

 one bee was occupying the burrow. This enabled me to select, 

 with a certainty, burrows that were occupied by only one bee. 



The following series of experiments was performed upon a 

 bee that occupied a burrow all to itself. The burrow was situ- 

 ated in a small barren spot and surrounded by a few blades of 

 grass, which partially covered the opening. The heads of several 

 stalks of grass overlapped the barren spot. The bee arrived at 

 9:35 A. M. and immediately entered the burrow. At 9:37 A. 

 M., it departed again for the field, without stopping to explore 

 •the surroundings of the nest-opening. 



Experiment i. 



While the bee tvas afield, a rectangular piece of white paper, 12 

 cm. by 8 cm., in the coiter of zuhich was a hole ij nun. in diam- 

 eter, was so adj2isted over the nest as to have the hole in the paper 

 coincide zvitli the opeimig of the burroiv. 



At 9:55 A. M., the bee arrived with its burden of pollen. In- 

 stead of entering the nest, it circled around and around. It then 

 hovered, momentarily, over the white rectangle and then de- 

 scribed yet wider circles in the air. This behavior was repeated 

 several times. At 9:57 A, M., two minutes after its return from 

 the field, the bee entered the nest. On again departing for the 

 field, at 10:00 A. M., the bee hovered a while above the paper 

 that surrounded the nest ; then, after making several turns of a 

 helicoid curve, flew away. 



' To determine how many bees were occupying a burrow, I would plug the open- 

 ing and then observe it carefully for an hour or longer. The bees, on returning, would 

 circle about the nest. After a while they would usually try to dig around the plug. By 

 counting the bees that appeared and tarried it was easy to determine how many bees 

 were occupying the burrow. When the required information had been obtained, the 

 plug was removed. 



