138 BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 4, NO. 4. 
At 11:8:50 the bee returned to the opening, but seemed 
greatly disturbed, and did not enter until 11:9:10 (20 seconds 
later), after a thorough examination of the leaf by flying around 
it and behind it a number of times. It left as usual. 
At 1 1 : 1 1 :28 it was back again, but entered only at 11 :ii :35, 
7 seconds later, and in the meantime made an inspection of the 
leaf. This it also did at the next visit at 11 :13:5c, but it went 
into the nest 3 seconds later at 11:13 :53- At 11 :i6:iO it entered 
directly, without any hesitation, and from this time on it did not 
seem to pay any attention to the leaf whatever. 
These experiments show that the solitary bee under discussion 
is capable of adding new visual impressions to its memory within 
a short time. It learns easily, and soon becomes acquainted with 
changes in the surroundings of its nest. In the first experiment 
the insect was guided by the new impressions from the sixth visit 
on, although the previous impressions had been the dominating 
ones throughout a comparatively long period. It is also interest- 
ing to note how from visit to visit the time spent in studying the 
new surroundings became shorter. The insect had evidently less 
to learn on each subsequent visit until it had become entirely 
familiar with the situation. In the second experiment the insect 
had overcome the difficulty at the fourth visit, and the time 
spent in studying the altered conditions was much less than 
in the first experiment. It would therefore seem that by changing 
the site of the nest we confront the bee with a more difficult task 
than by changing the appearance of the nest-entrance. 
The actions of this bee when dealing with changes in the 
topography of the surroundings of its nest are identical with those 
exhibited when it has undertaken the building of a new nest. In 
each instance it submits the region around the nest to a thorough 
and repeated inspection, and keeps the visual impressions resulting 
therefrom in its memory. This is quite in accordance with the 
facts obtained for social bees and wasps as referred to at the be- 
ginning of this paper. 
B. Argyroselenis minima Bob., a parasitic bee. 
While watching a nest of the leaf-cutter bee, Megachile lati- 
manus, at Cedar Lake, Washington Co., Wis., on the afternoon of 
July 13, 1903, I noticed a parasitic bee, Coelioxys ruiltarsis, mak- 
