Moth Wings Detect Smells Using Specialized Chemosensory Structures

Insect wings are packed with sensory equipment, but the question of whether moths could truly “smell” with their wings has remained largely open. New work from Sonja Bisch-Knaden and Bill Hansson at the Max Planck Institute for Chemical Ecology now shows that hawkmoth wings are more than touch-sensitive—they have an olfactory capability that can help guide egg-laying choices.

The researchers focused on the tobacco hawkmoth, Manduca sexta. By examining the wing surface at high resolution, they looked for the biological hardware expected for smell detection: specialized odour-sensitive hairs distributed across the wings.

Their imaging and measurements revealed two key hair types embedded along the wing edges. Alongside slender touch hairs (~120 μm), they found shorter, stubbier porous hairs (~80 μm), a structural signature consistent with scent sensing. But morphology alone can’t confirm smell—so the team tested the wing’s underlying molecular machinery.

Using wing tissue to collect messenger RNA, the researchers mapped odor-related receptor genes. They identified mRNA for 33 taste and scent receptors in total, with 15 specifically expressed along the wing edge where scent hairs cluster.

Next, electrical recordings provided functional evidence. When airborne odor puffs were delivered to a prepared wing, most tested chemicals elicited little response—except two malodorous amines: pyrrolidine and piperidine. These compounds occur in the leaves of nightshade plants, which are the insects’ preferred sites for laying eggs.

Even when the wing edges were trimmed away, the moth wing still detected these same amines, implying that smell-detection hairs are not confined to edges alone. The sensing system appears distributed across the wing surface.

To pinpoint which receptors might be responsible, the researchers used AI-based modeling to predict three-dimensional protein structures. They then computationally docked pyrrolidine and piperidine into candidate receptor binding pockets, finding that two receptor candidates could plausibly bind both molecules and trigger the sensory pathway.

Taken together, the results establish that hawkmoth wings carry functional odor receptors and matching sensory structures, effectively giving the insect a wing-based nose. The study, published in the Journal of Experimental Biology, links this wing olfaction to ecologically relevant host-plant chemistry.