82 
Psyche 
[June 
available. The bee is still to be found only at White Rocks. Is 
it possible that it arose here in its evolution? 
SUMMARY. 
1. Perdita opuntice is a wild bee which has been reported 
from nowhere else but White Rocks, Colorado. 
2. It is isolated here because it must make its nest in sand- 
stone. 
3. The isolation of White Rocks by large areas of tilled 
land prevents the spread of this bee. 
4. It visits the flowers of but one plant species, the cactus, 
Opuntia mesacantha Rafinesque. 
5. There are several entrances and about ten inhabitants 
to each nest. 
6. The bees usually alight several times on nearby rocks 
before entering their nests. 
7. In some cases, the inhabitants have the peculiar habit 
of disappearing into the sand to gain entrance to their nests. 
8. Perdita opuntice is to be found at White Rocks during 
the latter part of May, all of June and early July. 
9. This is apparently the first bee reported to make its 
nest in stone. 
BIBLIOGRAPHY 
1. Bequcert, J. 
’20 Hymenoptera Collected near Boston, Mass., with Des- 
cription of a Variety of Bombus affinis. Psyche, 27 : 6-12. 
2. Cockerell , T. D. A. 
’96 The Bees of the Genus Perdita F. Smith. Proc. Acad. 
Nat. Sci. Philadelphia, 48: 25-107. 15 figs. 
3. Cockerell , T. D . A. 
’00 The Cactus Bees; Genus Lithurgus. The Amer. Nat- 
uralist, 34: 487-488. 
4. Cockerell, T. D. A. 
9 11 A List of the Bees of the Genus Perdita Smith. Psyche, 
18: 134-143. 
