Carpenter bees can be distinguished from bumble bees by the carpenter's

• A. Larger wings
• B. Color pattern
• C. Wing length
• D. Bare top of abdomen

Answer: (D)

The distinguishing feature being tested is the texture of the abdomen on the dorsal (top) side. Carpenter bees have a smooth, shiny, largely hairless abdomen, so the top of the abdomen appears bare. Bumble bees, in contrast, are quite hairy on the abdomen, often with distinct color bands. This difference in dorsal hairiness is a reliable field mark that lets you tell them apart without relying on size or wing characteristics, which can vary.

So the bare top of the abdomen is the best clue for telling carpenter bees from bumble bees. The other options—wing size, overall color patterns, or wing length—aren’t as dependable because these traits can vary within species and aren’t consistent identifiers.