1926] Phenology of Inquiline and Nest-making Bees 119 
Emphoridce, Euceridce and Triepeolus. — The Euceridse fly 
198 days, Apr. 8-Oct. 22. Excluding Tetralonia, they fly 132 
days, June 13-Oct. 22. Triepeolus flies 118 days, June 26-Oct. 21, 
all together for 5 days, Aug. 30-Sept. 3. 
In 4, 37, I accepted Ashmead’s erroneous opinion because 
Triepeolus was mixed with Epeolus. There were too many of 
them and they were too large to be inquilines of Colletes. 
Triepeolus donatus, Aug. 11-Oct. 11 infests Melitoma taurea, 
June 24-Oct. 7 (Ashmead in 5). T. helianthi, Aug. 11-Oct. 3, 
infests Melissodes trinodis, June 14-0ct. 6 (Graenicher 2). T. 
pectoralis , Aug. 30-Oct. 21, coincides pretty well with M. autum- 
nalis Aug. 21-0ct. 22. Triepeolus is too late to infest Tetralonia. 
Tetralonia dilecta , Apr. 18-July 14, may be infested by Holono- 
mada superha, Apr. 20-June 24. 
Of 296 local species, the short-tongued bees are 50.6 per 
cent. In general they are the primitive bees and occupy the 
original positions. The long-tongued bees, developed later, have 
turned to flowers whose nectar has become so deeply seated as to 
be rather inaccessible to the short-tongues. They have not dis- 
placed the lower bees, but have taken up new ecological positions. 
That the long-tongues have been compelled to find new places for 
themselves is shown in the development of inquilines, 77.7 per 
cent of which are long-tongues. Inquilines are 38.3 per cent of 
long-tongued bees and 10.6 per cent of short-tongued bees. 
Of the short-tongues, the Halictidse are the only ones which 
have developed inquilines, Sphecodini and Paralictus. Natural 
selection seems to have favored the development of inquilines, 
just as if they could live at the expense of previously established 
bees better than they could actively compete with them. 
About the only adaptive characters shown by inquilines are 
differences in size. They run smaller than their hosts and the 
small species belong to small hosts. 
The characters by which the species may be distinguished 
are unusually non-adaptive. The mutationists, with whom the 
origin of species seems to be the same as the origin of specific 
characters, might readily point to inquilines as species with 
whose origin natural selection had nothing to do. 
The inquilines, however, generally, if not always, have 
