140 BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 4, NO. 4. 
again, and enters the nest at 12:10:15 p. m., staying in nntil 
12 :11 :20. It then spends nearly 6 minutes studying the territory 
around the nest, at first only the immediate vicinity, but gradu- 
ally extending its excursions to a distance of 3 m. to the east 
and west, also above, flying over the top of the bank, and below. 
It frequently returns to take a look at the nest, and dt rarely 
ever passes through the neighborhood of the latter without tak- 
ing notice of it. At 12:17 it departs but is back again at 12:31, 
and this time, judging from its behavior, it is less excited than 
at first, it displays a certain familiarity with the surroundings, 
and leaves again after looking at the nest. 
August 13. 
I arrived at the nest at 11:14:30 a. m. The parasitic bee 
(probably the same specimen) was already there, sitting on a 
rootlet above the nest. At 11 :15 :10 the host-bee arrived, entered, 
and left again at 11 :26 :25. During these 11 minutes the parasite 
became impatient, and changed its position quite frequently, 
sometimes sitting to one side of the nest, sometimes to another 
on some small plant, but always facing the nest. It usually 
took a glance at the latter when flying from one plant to the 
other. It acted as if more at home and much more unconcerned 
than yesterday. It remained quiet for about 20 seconds after the 
departure of the owner, and then it visited the nest, remaining 
inside only about 15 seconds. After this several excursions along 
the bank on both sides of the nest were made, the parasite 
always turning its head towards the nest when passing by. It 
then left. Its behavior on this day pointed to an intimate ac- 
quaintance with the locality. At 12:8 p. m. I went away, and 
up to this time the parasite had not returned. 
August 14. 
At 9 :36 :20 a. m. I visited the nest and found Colletes engaged 
in clearing out the nest. Argyroselenis was already there, flying 
around the nest, but before long it alighted on a leaf nearby. I 
felt certain that I had been dealing throughout these days with 
the same individual of Argyroselenis minima, but in order to 
leave no doubt about this I caught the specimen at 9 :40, marked 
the back of the mesothorax distinctly with a bright red crayon 
and set it free. It flew away and had not returned again at 
noon, when I left. 
