1929] 
Oligolectic Bees and Favorite Flowers 
113 
Correlation of Oligoleges and Flowers 
Of 84 oligolectic bees listed in 4, 426-7, fourteen are 
omitted here because their females have not been observed 
enough to establish their time of flight, or visits. 
In the case of the other 70, the flowers which they visit 
for pollen average 102 days. The bees average 60 days, 20 
days after the flowers begin and 22 days before the flowers 
end. This is not a close correlation, but the time of the bee 
should be well within that of the flowers. Three show the 
average of 42 days, 34 show less and 34 show more. The bee 
can hardly be expected to collect pollen until several days 
after it begins to fly, but it is fairly necessary that it should 
find the flowers in bloom. It is even more necessary that the 
flowers should bloom later, so that the bee can work up to its 
last day. 
Details 
Colletes oligoleges. Colletes aestivalis , 55 days, begins 4 
days after and ends 3 days before Heuchera hispida, 62 days, 
May 4- July 4. C. brevicornis, 32 days, begins 9 days after 
and ends on the same day as Specularia perfoliata, 41 days, 
April 20- June 29. C. willistonii, 101 days, begins 17 days 
after and ends 29 days before Physalis y 147 days, May 11- 
October 4. C. latitarsis, 108 days, begins 36 days after and 
ends 3 days before Physalis. C. armatus, 46 days, begins 25 
days after and ends 24 days before the Asterese which it 
visits, 95 days, July 29-Oct. 31. C. americanus, 73 days, be- 
gins 27 days after its Asterese and Helianthese, 100 days, 
July 24-Oct. 31, and ends on the same day. C. compactus, 48 
days, begins 47 days after and ends 10 days before its Com- 
positse, 105 days, July 19-Oct. 31. These Colletes range from 
32 to 108 days, and are short or long to agree with their 
flowers. Only two, C. latitarsis and willistonii , get pollen 
from the same plants. 
Andrenid Oligoleges 
Salix oligoleges. The willows bloom from March 17 to 
August 11, 148 days. The 6 oligoleges, whose flight-times 
are pretty well made out, fly from 46 to 88 days, average 86 
days shorter than the season of Salix. They average 10 days 
