Never mind the knees, how about those tongues?
Check out the tongue between the down-turned antennae. (Those antennae, by the way, are hugely important sensory organs: they can touch, taste, and smell.) There are short-tongued and long-tongued bee species.
This leaf-cutter bee seems to be tasting this stem.
This one explored numerous leaf edges. The tip of her tongue looks very rough… it’s hairy. I guess she’s looking for the right leaf to cut? She uses these pieces of leaf to line her nest. This Univ. of Florida site gives good information on leaf-cutters, but then says “Leafcutting bees can be considered a pest because of leaf cutting on ornamental plants.” No, no, no! Isn’t this infuriating? It’s nineteenth century gardening nonsense in the 21st century. Human aesthetics, another thing killing the planet.
Wear those circular cuts in plants as badges of pride!
This poor Bombus didn’t make it. She died with tongue out (unless it’s a male?). With some magnification, the tip of the tongue is seen in all its roughness. The flanking parts are mouth bits, maxilla perhaps, or palpi?
By the way, the wings are hairy too. Sparse, short black hairs.
Always reverence for god’s smallest and undervalued creatures