Winter moths

We have a few moths that only emerge once the frosts have arrived. At first glance, this seems to be a flawed plan, since there is little vegetation to support caterpillars and the low temperatures are a hindrance to cold-blooded species (and none of our butterflies have this 'alternative' lifestyle plan). But a bit of investigation reveals that these winter emerging species might actually have a couple of advantages. Firstly, there are no ichneumonids or tachinids around to parasitise them at this time of year. Secondly, there is much less competition for any limited food resources that do exist. Thirdly, the eggs stay inert for a while, so their caterpillars don't hatch until fresh leaves are available, and they pupate before the real competition for summer food arrives. (This early pupation also provides some limited protection from parasites and predators). Furthermore, male moths are generally guided to the female by smell, and the summer moths can travel great distances overnight as they search for a mate, but many (not all) of the winter emerging moths have flightless females that stay in one place after they hatch. This means that the males have much less hunting to do to find a mate, which is a bonus in cold weather. There are some summer-hatching species with flightless females, so it would be interesting to know which came first: the winter hatching or the flightless females. More research, I think.

Here are a couple of winter moths which I photographed in December:

I photographed this very fresh (the abdomen is clearly still pink) Pale Brindled Beauty on the 19th of December, although its normal peak season is in March. This tied in with my sightings of Bumblebees, Celandines, and Willow leaves and catkins all around the same time: all of those would be much more normal in March than December.

Pale Brindled Beauty

I have subsequently discovered that this is the earliest ever date (by one day!) in Ireland for Pale Brindled Beauty to be recorded.

I also saw the very handsome Mottled Umber on December 25th:

Mottled Umber

At first I thought that this was a new species for me, because I had certainly never seen the moth before, but my records show that I had photographed the caterpillar in 2006 (you can see it here). So it's a new adult moth, but not a new species for me.

Both of these moths feed on leaves of a wide range of trees when caterpillars. In each case, the photographs show males, because the females of both species are wingless.

For the last week or so, the wind has been mostly from the south, and I received reports that immigrant moths have been found in the south of the country. I didn't think that they would bother at this time of year: perhaps it's yet another sign of a mild winter to come.

A moth!

This is the first moth I have been able to photograph since around November.

The Pale Brindled Beauty - Phigalia pilosaria - normally flies from January to March, but early specimens can be found in December.

Pale Brindled Beauty - Phigalia pilosaria

There are two main colour variants: the first - like mine - is mostly pale, but specimens found in the centre of large cities tend to be almost uniformly dark grey. This is a clear example of selective mutation, where species increase their chances of survival by favouring colour forms that best match their surroundings. Evolution is generally thought to take place over many thousands of years, but it's clear that adaptation can take place in a few hundred years where situations demand. Clean air (like mine, which is washed most days) = pale specimens: polluted air (as found in large cities, with associated sooty deposits) = dark specimens. There are quite a few moths where this variation in colour distribution is the norm. In each case, the pale form is found on my patch.

The specimen in my photograph is clearly a male, since the female - in common with many of the winter moths - is flightless.

Slight heat

Last night was slightly warmer than it had been recently, so I had a quick check at the porch lights just in case moths were active. 

This male Pale Brindled Beauty had tried to get as close to the *light as it possibly could:

Male Pale Brindled Beauty - Phigalia pilosaria

Again, these have flightless females, and they appear in two main colour forms: in rural areas they tend to be as shown above, and in industrial areas or cities, they are often much darker.

The Chestnut is a bit atypical of the winter moths, since it is patterned and coloured like many of the moths from much later in the season (it also belongs to a different family - the Noctuids):

Chestnut moth - Conistra vaccinii

Both of these moths can be found during the coldest months, so they aren't really a sign of the forthcoming spring, but they do bring a smile nevertheless.

* this is a very interesting lightbulb, as it attracts many night-flying moths; it's one of the newer energy-saving bulbs that's shaped to look very much like the old incandescent bulbs.

Spring!

Today I first heard, and then saw, dozens of frogs in courtship. No spawn yet, but I'd bet on finding some by the weekend.

It's interesting to note that the Pale Brindled Beauty moth - Phigalia pilosaria - is at the end of its season (December- March), when most moths are still safely tucked away in their cocoons:



Still no Willow leaves, although the buds are most certainly getting larger. Again, I think bud break will be this week.

Given the sudden rise in daytime temperatures, I'd expect to see queen bumblebees and the earliest hoverflies out and about soon, too: I got buzzed by a Bluebottle earlier in the week.

New (to me) moth

A couple of these came to light. One outside the house, the other inside.

Pale Brindled Beauty - Phigalia pilosaria.


Both were males: the females are wingless.

This broad-leaf species is regarded as scarce in NW Ireland, but is probably just under-recorded.

Not quite the beauty that its name would suggest....I rather think the people who gave the names out were having a bit of a giggle to themselves.

This is a species that has two forms: one dark, the other pale. The dark version flourished in polluted places like central London, where it still outnumbers the pale version by 60:40. Ours are pale, of course.