Flies, Clark and Emonet concluded, must sense the motion of odor packets, as Emonet calls discrete clumps of odor molecules. Think about this for a second: When you smell the neighbor’s barbecue, can you tell whether the smoke particles passing your nose are traveling from left to right, or right to left? It’s not obvious. But a fly can tell — and olfaction researchers have previously overlooked this possibility.

— Read more in Scientists Are Trying to Figure Out How Animals Follow a Scent to Its Source at Smithsonian.