On the surface the abdomen has no special outside structures, but is the center for digestion and reproduction (for drones and queens). It also houses the sting, a powerful defense against us humans. The digestive tract is rather typical for an insect. The esophagus starts near the mouth, goes through an opening in the brain, through the thorax, and enlarge near the end to form the honey crop, which can expand to quite a large volume (nearly half of the abdomen in a successful forager). There is a special structure called preventriculus near the end of the crop. The proventriculus has sceleritized teeth-like structure, and also muscles and valves. These structures allow the workers to remove pollen grains in the nectar, and also stopping the backflow of food being digested into the crop, ensuring that the nectar is never contaminated. The contents of the crop can be spit back into cells, or feed to other workers, as is the case of nectar collected by foragers. The ventriculus (midgut) is the functional stomach of bees and is the largest part of the intestine. Malpighian tubules are small strands of tubes attached near the end of ventriculus and functions as the kidney, it removes the nitrigen waste (in the form of uric acid, not as urea as in humans) from the hemolymph and the uric acid forms crystals and is mixed with other solid wastes. The rectum is also quite expandable (just like the crop, and both are extoderma structures, and both are lined with a chitin layer, enabling workers to refrain of defecation for up tomonths (for example bees in Michigan here might have their last defecation flights in November, and then again in March the next year).

Sting.

Reproductive system.