Below is a drawing I did showing the difference between a winter and a summer bee’s abdomen. The colours are for fun and to show the different parts more distinctly, obviously the bee is not really pink, blue and yellow inside!
In the summer, you can see the bee’s crop, her nectar collecting stomach, is enlarged. In the winter, when a bee has been stuck inside the hive for several days due to cold weather, waste builds up in her rectum – that’s the big pink shape – and the rectum enlarges to take up nearly the whole abdomen. A bee will never deliberately defecate within its home, so if you see brown trails of poop on the combs you know something is really wrong.
The ventriculus is the light blue segmented shape you can see. It’s the main digestive organ of the bee. In the summer bee’s abdomen it has plenty of space, in the winter bee’s abdomen it has been pushed right up as the rectum enlarged.
The white worm-like shapes you can see are the malpighian tubules. About a hundred of these connect into the digestive system, joining the gut at the junction between the ventriculus and the small intestine. The small intestine is the light pink curl leading into the rectum. The malpighian tubules absorb waste products excreted by the various organs into the bee’s haemolymph (the equivalent of our blood) and pass them into the small intestine for disposal.
It seems so clever to me that a bee’s organs can move around that much to accommodate the different lifestyles of a summer and a winter bee.
- Understanding bee anatomy: a full colour guide by Ian Stell (The Catford Press, 2012)