13 August 2016

Honey Bee Flower Constancy

A careful observer will notice that honey bees will usually visit just one type of flower when out foraging, this is known as "flower constancy", and yet...

Honey bee on Purple Loosestrife
Honey Bee on Purple Loosestrife
Photo M.Malcher 2016

Flower constancy has been known for millennia, Aristotle wrote:
"On each expedition the bee does not fly from a flower of one kind to a flower of another, but flies from one violet, say, to another violet, and never meddles with another flower until it has got back to the hive." (The History of Animals Book IX, Part 40)

European honey bees usually collect either just nectar or just pollen on a single foraging trip, they are highly "flower constant" which is what makes them particularly valuable for pollinating commercial crops. When foraging for pollen the honey bee's pollen baskets will be from a single source 81% of the time.
 (Insect-Plant Biology. Louis M. Schoonhoven, Joop J. A. van Loon, 2005)
The why and how, when and where of honey bee foraging has been the subject of a vast amount of scientific literature. 

To return to my photograph above. Given the location, this is probably one of my bees. She is foraging on Purple Loosestrife. On her back there is white pollen from Himalayan Balsam - easily picked up due to the structure of the balsam flower. Watching our white dusted foragers return at dusk, beekeepers sometimes call these "ghost bees".
Bee emerging from Himalayan Balsam Flower
Photo M.Malcher 2016
I watched her for several minutes, happily foraging in both plants, she seemed to be foraging for nectar rather than pollen.
Maybe this bee was just more adventurous than her sisters, yet having been away to "read the books" after observing her, I have the feeling that there are still far more questions than answers.

Links that may be of interest

Rusty Burlew of Honeybeesuite - a good, clear explanation about nectar and pollen collection by honey bees:

Functional Ecology, 2012 (British Ecological Society)

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