Friday, July 16, 2010

Bumblebees galore!

This year we seem to have a lot more bumblebees than honeybees in the garden. I have even observed bumblebees bullying honeybees from a flower. I decided to investigate further about them:

*They remove nectar using their long tongue called a glossa and store it in their crop or they will bite directly into the corolla called nectar robbing.

*Some species will leave a scent to mark that the flower has been visited – I wonder if honeybees do the same and if they can also can detect the scent left by the bumblebee.

*Once they have collected the nectar, they return to the nest and deposit it into brood cells made of wax but do not process it as honeybees so it is diluted and watery. It can only be stored for a few days unlike honey which can last indefinitely.

From this amazing site(, here is some very interesting information regarding honeystomachs:

Bumblebees gather nectar into their honeystomachs to transport it back to the nest. The honeystomach is located in the abdomen, and it is just a cuticle-lined bag with a long neck located at the mouthparts. It holds 0.06 - 0.20 ml, depending on the size of bumblebee, and when full can take up as much as 95% of the abdominal space and hold 90% of the body weight.

During foraging the bee needs energy, so she will consume some of the contents of the honeystomach. To allow her to do this there is a small valve at the end which can allow some of the nectar to pass into the bee's own digestive system. It has been estimated that a full honeystomach will give a bumblebee about 40 minutes of flying time.

Some flowers contain as little as 0.001 ml of nectar, so to fill her honeystomach the bumblebee may have to suck nectar from 60 flowers, and to find these 60 she may have to visit 100 or more. Then she will return to the nest, which may be as much as two miles away. So providing a supply of nectar for her nestmates would not be possible without the honeystomach to carry it in. A teaspoon holds about 5 ml and nectar is about half water, so to fill a teaspoon of honey a small bumblebee might need to make over 80 foraging trips, flying up to 320 miles, and sucking 80 000 flowers! Honeybees also have a honeystomach, and as they are smaller than bumblebees they would have to make even more foraging trips. Think of that next time you spread honey on your toast!”

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