Insect wings are bristling with senses, feeling the wind blowing and even tasting potential mates, but little was known about whether moth wings are equipped with a sense of smell. Sonja Bisch-Knaden and Bill Hansson from the Max Planck Institute for Chemical Ecology, Germany, had a hunch that moth wings might be able to sniff out certain aromas. Taking a close look at the surface of tobacco hawkmoth ( Manduca sexta ) wings and measuring the electrical signals produced by the wing, Bisch-Knaden and colleagues publish their discovery in Journal of Experimental Biology that the moth’s wings have a sense of smell and can sniff out the plants that they lay their eggs on.
Bisch-Knaden says, ‘The tobacco hawkmoth was recently found to have receptor proteins in its wings that could detect different smells and tastes’. But receptor proteins are only the beginning of the sensory cascade that converts scents into nerve signals to transmit the sense of smell. She knew that tobacco hawkmoth wings would also require specialised odour-sensitive hairs distributed along the edges of their wings to have a true sense of smell. The team looked for the essential scent hairs.
After gently snipping the edges from tobacco hawkmoth wings, Ahmed Ismaieel (Max Planck Institute for Chemical Ecology) carefully sprayed a fine mist of gold over the portions before scrutinising them with a scanning electron microscope.
Interspersed between slender (120 μm) touch sensitive hairs, Ismaieel could see stubbier (80 μm) porous hairs, the hallmarks of scent sensors, suggesting that the shorter hairs might contribute to the insect’s sense of smell. But could the wings actually sniff an odour?
To begin answering the question, Ismaieel and Regina Stieber, also from the Max Planck Institute for Chemical Ecology, collected mRNA from the insects’ wings (which codes for the proteins that recognise specific scents).
After months of painstaking analysis, they identified the mRNA for 33 taste and scent receptors, with the mRNA for 15 receptors produced along the wing’s edge, where the odour-sensing hairs are located. And when the team cross-referenced the receptor proteins that they had found in the wing with the odours that the receptors sense in other insects, they concluded that the moth’s wings likely sense bitter flavours and the aroma of amines, which smell like rotting fish to us.
But which odours could tobacco hawkmoth wings sniff out in practice?
Ismaieel rigged up a wing to an electrical circuit and blew puffs of odours – from putrid pyridine and fruity methyl hexanoate to the heady scent of Datura flowers – onto the wing, to find out which scents the wing could smell.
Surprisingly, the wing only picked out two odours, pyrrolidine and piperidine, both of which are stinky amines that are in the leaves of nightshade plants, upon which tobacco hawkmoths prefer to lay their eggs.
And when Ismaieel trimmed the edges off the wings and retested their sense of smell, he found they could still detect the unpleasant amine odours. ‘This suggests that the moth has special sensory hairs across its wings, not just along the edges, that can smell those odours’, says Bisch-Knaden.
But which receptor proteins could be responsible for the wing’s sense of smell?
This time, Ismaieel turned to AI to predict the 3D structures of ten of the potential odour-smelling proteins, before attempting to fit pyrrolidine and piperidine – the two molecules that the wing can smell – into the receptor protein pocket, to allow them to mediate the sense of smell.
Ismaieel got hits. Both of the stinky molecules fitted snuggly into the binding pocket of two of the candidate receptor proteins, which could allow the proteins to trigger the sense of smell. So, tobacco hawkmoth wings definitely have a sense of smell, which could help direct them to their favourite plants for laying eggs.
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REFERENCE: Ismaieel, A. R. Stieber, R., Hansson, B. S. and Bisch-Knaden, S. (2026). Noses on the wing: the olfactory capacity of hawkmoth wings. J. Exp. Biol. 229 , jeb252047.
DOI: 10.1242/jeb.252047
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Journal of Experimental Biology
Experimental study
Noses on the wing: the olfactory capacity of hawkmoth wings
27-Jul-2026