Copyright Broadacre Garden
Bumble bees are harder to deal with his way as you rarely see them in large numbers in one place. In the end I found that by using just “1” and “3” for my observations the average of the observations came out within the usual range and the numbers for bumble bees were then on a scale directly comparable with honey bees. Comparison is a lot easier if the same number means the same thing in terms of relative attractiveness.
We should remember that an average of arbritrary numbers is just a descriptive term of something in between the extremes. It is not a true average.
When I say Bumble bees I mean all bees other than honey bees. I don’t want to leave the other bees out but I cannot identify them all and separating records for dozens of species would get too complicated anyway.
Other people have monitored flower attractiveness in other ways. To read about these go to other observers. E.g Garbuzov & Ratnieks also Rosi Rollins and Whitney Cranshaw. The first two are more carefully controlled from a scientific point of view. Cranshaws (this is from Colorado, USA) is more subjective, like my own.