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IOWA ACADEMY OP SCIENCE Vol. XXIV, 1917 
On the whole, bumble bees are shown to be quite efficient pol- 
linators of red clover. 
H. S. Coe summarized the previous investigations in regard 
to the honey bee as follows : 
HONEY BEES AS CROSS POLLINATORS OF RED GLOVER. 
The ability of the honey bee to cross pollinate red clover has 
been discussed by scientific investigators and bee keepers for 
some time. Those who do not believe that the honey bee is able 
to pollinate red clover base their statements for the most part 
on the fact that the proboscis of the honey, bee is not long enough 
to reach the nectar located at the base of the staminal tube. 
Some investigators and bee men state that some strains of the 
Italian race of honey bees are able to obtain some nectar from 
red clover flowers while other investigators say that honey 
bees collect pollen from red clover flowers and thereby cross 
pollinate them. 
According to Knuth 20 the proboscis of the honey bee is 6 mm. 
in length, which is 3.6 min. shorter than the average length of 
the corolla tubes of first crop red clover flowers. Pammel states 
that nectar lies from 7 to 9 mm. deep. Honey bees may be able 
at times to obtain some nectar from the sides of the staminal 
tubes of red clover flowers when a large amount is secreted, or 
when the flowers are not in an upright position. On pulling the 
red clover flower out of the calyx the nectar is visible to the 
naked eye. J. H. Frazier found that in rainy weather the nec- 
tar may be reached at a depth of 6 mm. from the upper part of 
the tube of the corolla, but in dry weather the nectar was found 
at a depth of 8 mm. Chemical analyses of the nectar washed 
from clover corollas, however, show that in rainy weather it is 
not very rich in sugar. Indeed, much of the accumulated liquid 
may be rain water drawn by capillarity into the corolla. It 
w r as also found that the amount of nectar secreted varied greatly. 
After a heavy dew on July 20, 1915, the amount varied from a 
small drop at the base of the tube to 6 mm. The tightly fitting 
calyx evidently crowded the nectar up. The small corolla tube 
causes the nectar to rise by capillarity. 
Opinions differ as to whether honey bees actually collect nec- 
tar. Dadant 17 makes the statement that honey bees do sometimes 
collect nectar because of the shorter corolla tubes. The same 
statement is also made by A. I. Root. 21 
