Couldn't find any pictures of the females of this species on iSpot so I've added one.
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Thanks for adding this. It's an interesting phenomenon. Presumably losing wings and the associated muscles raised fecundity and was therefore favoured by natural selection during the evolution of these moths. Males, of course, need wings to find females!
University of Edinburgh and Biodiversity Observatory (OU)
Interestingly a lot (although not all) of the British moth species with wingless females are winter flying species.
I would think that flying is more costly in winter (the need to warm the wing muscles up from a colder starting point for instance) and the availability of fuel sources (e.g. nectar) is much lower. However it seems likely the advantages to flight (predator avoidance, dispersal, foodplant location etc.) are no greater.
Perhaps this creates an evolutionary pressure for winglessness to evolve in winter flying species.
All the moth species I am aware of in the UK that have a secondary evolved flightlessness have it only in the females.
Jonathan suggests that this is because the males need to find the females.
Presumably situations in which females find the males are possible.
Is anyone aware of any moth species where the males are flightless?
What about situations where both sexes are flightless?
The only moth species with flightless males also have flightless females - they're the 'grasshopper moths' of a few very windy Pacific islands. As far as I know they're only within the genus Thyrocopa (a new species is discussed here http://www.mapress.com/zootaxa/2008/f/zt01830p062.pdf).
I would imagine that the evolution of flightlessness would be favoured in females, rather than males, as a result of the energetic cost of flight: species where the female has to use energy both to produce eggs and fly, while the male becomes wingless and so has neither energetic demand, is highly likely to be less fecund than the alternatives of winged male/flightless female or winged/winged.
This means they would be less fit and so speciation wouldn't be favoured unless there is a vacant ecological niche, and especially when there is a means of overcoming the problem of dispersal - eg on a small, windy island, as with the grasshopper moths
Record your ladybird sightings!
Yes, or to put it another way, there is a difference between males and females in how reproductive costs translate into reproductive success. Sperm are cheap compared to eggs. The energetically costly bit for males is finding a female, not producing the sperm. So, diverting resources from flight to sperm would not increase reproductive success. For females, on the other hand, reproductive success is almost certainly limited by the number of eggs that can be produced, rather than any scarcity of males. Hence, if resources can be diverted from flying to egg production, winglessness can be advantageous for females.
Incidentally, reduced dispersal powers on islands is common in plants as well as animals. If you take to the air on a small island, there is a danger you will be blown out to sea.
Lat/Lng: 51.540316447216, -0.32921433448792
OS grid ref: TQ159837