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Weather is rubbish today for Butterflies (and Dragons), cloudy, cool Northerly breeze and some drizzle, but sometimes I just have to get out for at least a short walk. I couldn't help noticing that there were many day flying moths around the Gorse and Heather of the New Forest, not tiny little things but small butterfly size.

Is there some physical difference that enables these moths to fly in such conditions where butterflies won't, or is it just a question of desire/need?

Either this is so simple that I shouldn't be asking, or it's so hard that no-one knows.

I've observed exactly the same thing this afternoon in totally different habitat, not a single Butterfly or Dragon, but many moths.

Any chance of a clue please?

(These are both areas which I know reasonably well and they do produce the goods in better conditions).

Hi Ayjay. I don't know the answer (which is why I didn't reply) but I do know that different species have different means of raising the thorax temperature to that required for flight. Some (most butterflies) rely to a very large extent on radiant sunlight. Others can raise the temperature considerably by muscle activity. Many skippers do this, for example, and many moths too. Here is a chequered skipper I filmed in Switzerland warming up to get off the ground:

https://www.youtube.com/watch?v=j1RbYCEEAQs[/video]

This is complete speculation, but I suspect that a large thorax size compared to the wings, which usually means a more buzzing flight, is associated with insects that can generate a lot of heat and therefore fly in cooler conditions. Skippers and many moths fit this description - as do flies. Of course, some satyrids can fly in the rain even - but usually on days when cloud is interspersed with sun, when perhaps their dark colouring helps them heat up quickly.

Guy

You raise an interesting point, ayjay.

Moths certainly occupy a far wider range of habitats than butterflies. The most obvious example is that they can fly at night, when the air is much cooler, whereas many butterflies are only active in sunshine.

The most extreme example I know of is the Arctic Woolly Bear Moth (Gynaephora groenlandica) found within the Arctic circle. It was featured in the BBC TV series "Frozen Planet" The larvae can withstand temperatures below −60 °C by desiccating in the winter and re-synthesizing themselves in the spring. Each instar of the caterpillar takes about a year and the entire life-cycle lasts about 7 years!

Perhaps others will have more details but there is no doubt that there are mechanisms in many moths that allow them to survive and function in conditions where butterflies cannot.

Mike

Thank you both; I remember now seeing one of David Attenborough's programmes showing a species of bee which does a similar warm-up routine.

It obviously works, but given the time required to achieve flight it would not be very effective faced with threats from a predator.

I'm pretty sure that the moths I've been seeing are not warming up before flight; (they may already be warmed up by the time I'm seeing them), they are quite active and not just where disturbed by me.

I also remember seeing the programme with the Arctic Woolly Bear Moth Mike, but of course I'd forgotten, (getting old is bit of a bore).

There are obviously chemical differences in the make-up of moths and butterflies which are beyond what I have the desire to comprehend.

With any luck the weather will brighten and warm a little soon and I can get back to just watching them.