Nectar Thieves!

Our neighbors planted a morning glory vine along our property line. I was out there with my camera the other day trying to snap some pictures of carpenter bees which love the showy blue and purple flowers. These bees are so slow and loud it is fun to watch them.  I thought it would be easy to take a picture or two, so I took up a strategic position in front of a dozen flowers all lined up facing me. However, I kept waiting and waiting, and not a single bee went inside the flowers. I realized I was witnessing a fascinating phenomenon: nectar robbing.

By staying on the outside of a flower, carpenter bees take the nectar without pollinating

Morning glory flowers have long narrow throats that make it difficult for a big carpenter bee to climb inside.

Sizing up the throat: nope, too narrow

So they sit on the top of a flower, make a slit at the petal base (corolla) and get the nectar anyway.

Climbing to the top is hard work: fragile petals are crumpling and the whole flower is swaying precariously

Plants produce nectar as payment to pollinators for transferring pollen from flower to flower. By making a slit in the corolla, the carpenter bees avoid touching the pollen and therefore, take the payment without doing the job.

Almost there

That's why it is called nectar robbing.

Making a slit and getting to the nectar

A few flowers that I examined all had slits at their bases and there were no other bees that I could see, meaning probably that carpenter bees were pretty thorough in getting most of the nectar out.

The slit at the corolla: evidence of robbery

I have also witnessed a comic episode of a bee actually trying to climb inside a morning glory flower. After it got the nectar, it tried to get out backside first, lost its footing and fell out of the flower's throat.

A stumble bee?

It tried to grab onto a petal...




... but the petal folded, so it fell on its head again  (: .

Are they serving alcohol in there? Where do I line up?

Finally it climbed back in, turned around, and came out head first.

After all these antics, the flower was ripped apart, and probably completely useless for pollination.

I have read somewhere that it is typically female carpenter bees that cause so much destruction

I have to say these bees are not malicious by nature, and where a flower presents itself conveniently, they will take its nectar the conventional way and do their job as a pollinator.

Flowers on a sweet pea shrub make nectar easily accessible, so they get pollinated and I pull up hundreds of seedlings underneath the bush...

But they will do what they have to do to get their food :).