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Clearly a waste: the bee digestive system

The first line in the Huffington Post story reads, “An amateur photographer has captured an amazingly rare sight in his own back garden—a bee urinating.” No doubt, the photo by Mark Parrott is awesome, but is the bumble bee actually urinating?

In fact, the bee digestive system does not divide waste into solids and liquids—instead, all of it is collected in one place. The bee digestive system is more or less a straight line.

The bee digestive system

The mouth is connected directly to the esophagus, and the esophagus extends through the head and thorax all the way back to the abdomen. In honey bees, after food goes through the esophagus it travels into the crop (or honey stomach) where it is stored for transport back to the hive.

At the end of the crop is a one-way valve known as the proventriculus. Anything that passes through this valve moves on to the ventriculus (also known as the true stomach or digesting stomach) where it is digested. But anything that goes through the one-way valve cannot go back the other way. So food that is digested cannot re-enter the crop, and this is why nectar is not bee vomit. Nectar that will be used to make honey never makes it into the digesting stomach, only the crop.

The ventriculus is lined with cells that secrete enzymes that digest any nectar and pollen that has passed through the one-way valve. At the far end, the ventriculus is attached to the ileum, which is like a small intestine.

Right where the ventriculus meets the ileum, about one hundred malpighian tubules connect to the digestive tract. Malpighian tubules act like our kidneys. Just like our kidneys filter waste products from our blood, the malpighian tubles filter waste products from the bee’s hemolymph. This liquid waste, which is analogous to urine, is dumped into the ileum where it joins the solid waste from the ventriculus.

The ileum removes nutrients from the digested food and moves the waste further along the digestive tract. From the ileum, the waste products from both the ventriculus and the malpighian tubules move into the rectum where it is stored until the bee can defecate through the anus.

The waste stream of a honey bee

All bees are built in a similar way, but the crop is more developed in those species that carry nectar back to the nest. The flow of food and waste through a honey bee looks like this:

mouth↔esophagus↔crop (honey stomach)→proventriculus (one-way valve)→ventriculus (digesting stomach)→ileum (intestine)→[waste from malpighian tubules joins food waste in the ileum]→rectum→anus

So back to the photo, I would say the bee was defecating rather than urinating. But clearly she had a lot to drink that day. Who knows? Maybe she was getting ready for a mandatory drug test and was trying to flush away all the poppy nectar she drank.

Rusty
HoneyBeeSuite

Comments

Tom
Reply

Next week you need to give all your readers a pop-quiz on the bee alimentary tract!

Rusty
Reply

I like that idea.

Scott
Reply

I was wondering when you would comment on the photo. Love your take on it. I thought the bee was defecating also. It IS an awesome photo. As in “I am held in awe” that he managed to capture that exact moment.

Debbe
Reply

I love the fact that there is always something new and unexpected to learn about bees. Thank you so much for the explanation! (Will the quiz be open book?)

Tom
Reply

Rusty,
Your closing sentence brings me to a question I’ve been wondering about. Do bees get pollen from Cannabis sativa (marijuana) ?

Rusty
Reply

Tom,

A similar question came up last week about nectar. It seems that Cannabis doesn’t produce nectar and is wind-pollinated. But it is still possible that bees collect pollen from it, just as they do from corn, which also doesn’t produce nectar and is wind-pollinated. But I don’t know. Maybe someone with a plot could tell us?

John
Reply

Hi Rusty,

Any way it be venom ?

Cheers
John

Rusty
Reply

John,

It looks like too much, I think.

Greengage
Reply

good info tks

Glen Buschmann
Reply

Call it what you want, the photographer has my admiration. It may not be a bee wee, but it doesn’t look like a Bombus bolus either. I’ll let it pass.

jasna guy
Reply

Beautiful shot, really quite amazing. I wonder though if it might not be a tiny fine trail of dew-laden spider’s web? The bee might have flown through a strand while moving from flower to flower? (Noticed that the borage blossoms in the foreground also have dew on them).

Wonderful photography regardless and an equally wonderful opportunity for a super lesson on bee digestive tract!

Thank you.

Rusty
Reply

Jasna,

If you don’t trust this photo, see this one.

jasna guy
Reply

No room for conjecture or interpretation anymore!! Fantastic. Thank you!!!

aaldahri
Reply

Thank you Rusty for the informations .

Rusty
Reply

Thanks, Tim.

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