First flightless female Winter Moth of 2010

[Bruce Williams]

Stony Stratford, Bucks.

I love this species - such a strange life cycle. This is my first sighting for winter 2010 and what a beauty she is - absolutely pristine and not a scale out of place! Contrast this with one I posted in late November 2009:

10th Nov 2010


26th Nov 2009


Bruce

[basquesteve]

Its an interesting creature but at an evolutionary dead end how can it increase its range if under threat unless of course it has the knack of catching a lift in its life cycle

[Bruce Williams]

Thanks for your interest Steve.

Fortunately for the species it doesn't have to depend on the adults to increase its range. In common with many other species the Winter Moth uses a method of dispersion called "ballooning" during its early larval stage. It works this way:

After mating the female lays her eggs in various protected cracks and crannies (tree bark for instance) and then all the adults of that winter's generation die. Come the spring (temp ~13C) the eggs hatch and the young larvae start climbing tree trunks. When they have sufficient height they produce lengths of silk thread and use the wind to carry them to pastures new.

On the face of it this method does appear to be a bit hit and miss as it depends so much on wind strength and direction for efficient dispersal. However I guess it must work fairly well as there are many species using this same method with obvious success.

Bruce

[poschiavanus]

Interestingly they've managed to get to the Outer Hebrides (see the New Naturalist by Boyd and Boyd) (perhaps through accidental human dispersal). There are plenty of UK moths with wingless females, around 20 species in total. Males will come to light with attached female when "in cop.".

[basquesteve]

Originally Posted by Bruce Williams

Thanks for your interest Steve.

Fortunately for the species it doesn't have to depend on the adults to increase its range. In common with many other species the Winter Moth uses a method of dispersion called "ballooning" during its early larval stage. It works this way:

After mating the female lays her eggs in various protected cracks and crannies (tree bark for instance) and then all the adults of that winter's generation die. Come the spring (temp ~13C) the eggs hatch and the young larvae start climbing tree trunks. When they have sufficient height they produce lengths of silk thread and use the wind to carry them to pastures new.

On the face of it this method does appear to be a bit hit and miss as it depends so much on wind strength and direction for efficient dispersal. However I guess it must work fairly well as there are many species using this same method with obvious success.

Bruce

Thank you very much Bruce for the information this method had not occurred to me In the late summer here very young spiders use a similar method ! .There seems to be a flight time thousands of them on threads 10 feet or more any fencing or trees get covered in what looks like candy floss my face can get covered in the threads

Steve

[theresa dockery]

Fantastic photos Bruce!

Most moths with flightless females seem to emerge during winter or early spring...there must be some evolutionary advantages in winglessness somewhere...perhaps greater expenditure of energy on egg-laying rather than flight?

Conserving energy expenditure would seem more important in winter when there are very few flowers from which to re-fuel (if Operophtera even feed?).

I will try and find one myself this winter - if the snow holds off.

[charlie streets]

Hi Bruce, I've been searching for these flightless females on and off for a while without success. Is from dusk onwards the best time and do they prefer open woodland or are they just at home in more dense woodland in your experience.Also will they appear even on frosty nights? Any help much appreciated.

Charlie.

[Bruce Williams]

Hi Charlie,

Firstly welcome to the WAB forum .

Well I have mainly found them on the side of fence posts (occasionally on fence rails) at the edge of wooded areas. This may be because they are easier to spot than on tree trunks - after all they are quite small and blend in well with old gnarled wood. They have generally been near the top of the post and often tucked in near the joint where the post meets the rail.

I only search during daylight but have found that females don't seem to move much once they find a good spot near the top of a fence post. So I sometimes see the same female in the same location over several days.

Males are another matter entirely. Last year I saw just two males and I've seen and photographed one so far this year.

Good luck!

Bruce

[charlie streets]

Thanks for the welcome Bruce.

I had thought these moths had more discerning taste than climbing up any old fence post :-)

It's interesting to hear that some females stay on, and presumably lay their eggs on fence posts. You've done well to find them especially by day - photos of flightless female "winter moths" are always worth seeing.

I'll keep on searching.

Charlie.

[Farplace]

I hadnt realised until recently that there were wingless moths.... She looks amazing. Are they found in the Pennines? I would love to see one.