Dead Butterfly Blues

Back in the day when real men killed dinosaurs with their teeth and science was a disinterested search for the truth, it was permissible to say out loud that some species might benefit from global warming, as we naively called it then.

“Warm” being such a nice word, the desired threat level was not achieved, and so “climate change” was born. Of course we have now reached “climate breakdown.” [Note to Guardian journalists: using that phrase without blushing proves you are idiots. There is no climate breakdown, nor will there ever be, nor can there ever be: all that there is is a rising shriek of hyperbole accompanying a thousand hacks trying to blow gas into a giant green Zeppelin.]

Anyway, it soon became the case that any possible benefits arising from global warming had to be removed from public display, lest it dilute the message (an excellent recent example being the removal of a list of such benefits from the BBC’s bitesize revision site). Not only that: any good thing seemingly happening because of fine weather had to be heavily caveated. Thus we find what has become a standard portent of doom attached to any good news story:

“Species X has had an excellent year, researchers say, rebounding to record numbers from near extinction thanks to the fine weather this summer. But it remains threatened by climate change.”

Because everything is threatened by climate change, and nothing good can ever come of it.

Yesterday the BBC reported that the large blue butterfly has had a good year. On my first go through the article I merely skimmed the article to search for the obligatory acknowledgement:

Extreme weather and climate change also pose a danger, particularly because large blues rely on flowering plants and ant nests.

OK, so never mind that the sentence is nonsense. The required dose of salt was tossed over the shoulder into the Devil’s eye.

Anyway, this story gave me a chance to talk about insects, and I like insects. Let’s begin with the ebullience of the title:

Huge recovery for butterfly once extinct in the UK

Unalloyed optimism there. The large blue was only extinct in the UK for about 4 years, but it was extinct. The reporter – who shall remain nameless to spare her blushes – represents “BBC News Climate and Science.” Yes folks, we have reached the desperate strait when Climate is elevated as something separate from Science.

An endangered butterfly that was once extinct in the UK has had its best summer in 150 years.

I don’t know what happened in 1872 (Edward Newman’s British Butterflies was published in 1869), but on the face of it it looks as if the global warming we’ve had so far has benefitted this species. This would not be surprising. Butterflies generally like it hot. Most butterflies in the UK have a northern limit: any further north and it’s too cold. A few have a southern limit, like the Scotch argus. There are species like the Glanville fritillary that literally cling like limpets to the foot of southern cliffs. What butterflies hate are the miserable summers, the cold summers, the wet and dreary summers. The sunny summers, the hot summers, the dry summers: they love it.

Let’s rewind a sec:

Extreme weather and climate change also pose a danger, particularly because large blues rely on flowering plants and ant nests.

I said it was nonsense, and it is. You might as well say that the large blue is in particular danger because it is alive. Is there a butterfly in the world that does not rely on flowering plants?

The project saw conservationists focus on restoring a type of wild meadowland where the large blue likes to live.

“It’s one of the strangest butterflies in the world,” said Prof [Jeremy] Thomas.

It leads a very unusual life, spending most of the year as a caterpillar inside red ant nests where it feeds on grubs. This lifecycle makes it more challenging to protect.

This was a chance for the reporter to tell the interesting story about the large blue’s life history, which kinda got mangled. First, if we rewind to 150 years ago, the last time the large blue had a summer this good, and roughly when Edward Newman’s book on British butterflies was published:

Zeller tells us that the egg is laid on the wild thyme, and that the caterpillar feeds on that plant – a statement copied by myself in the previous editions of this history, and still, as yet, only partially confirmed.

Newman, 1874 edition of British Butterflies

So, 150 years ago the large blue’s life history was a puzzle, and I presume that caterpillars, collected together with wild thyme, failed to thrive in captivity. They disappeared in the wild too. What happens is that the caterpillar is collected by a worker of the ant Myrmica sabuleti and taken underground (see featured image). Its sweet secretions ensure that the ants look after it. Meanwhile, the caterpillar is chomping on not just “grubs” – but the grubs of the host ant.

Now the demise and resurrection of the large blue was, as you might expect, well known to students of ecology. The story was of a butterfly restricted to the south of England, and on south-facing slopes in the south of England, and on ground that was particularly hot because its turf was only an inch high due to grazing. A key point was that the large blue was widespread in mainland Europe, but was on the edge of its range in the UK. It was dependent on a thermophilic ant, and it was found in the hottest places on the hottest hillsides in the hottest parts of the UK. So if global warming was to have done anything, it would have helped, not hindered. But you have to have the other things: the ant, the thyme, the short turf. And even if you have those things, the large blue won’t automagically appear. Its adults are short lived. They don’t spread far. The suitable habitat is widely scattered and cut into small fragments. Without a friendly ecologist to carry the butterfly from one place to another, its extinction was assured. Its extinction is still assured without support because local extinctions are inevitable, and surviving populations elsewhere will be unable to recolonise the empty habitat.

When I was a student, the then Institute of Terrestrial Ecology published The greenhouse effect and terrestrial ecosystems of the UK (1990), of which I excerpt this:

and this little gem from the end of the report (Chapter 12: historical evidence of climatic change effects, by M. D. Hooper):

Four years later, the ITE investigated what climate change meant for rare species with Climate change and rare species in Britain:

In other words, species that might benefit from warmer weather will not be able to do so because of habitat fragmentation.

Here the population is described as having been reduced by anthropogenic factors (land use change, not carbon dioxide). The drought that finished it off was “freak climatic conditions.” Of course, if you are restricted to one place, it is expected that sooner or later the summer will be unsuitable entirely for survival and breeding. And even if you are in a place which is usually only just hot enough, there is always the chance that one year it will be too hot. And that would be that.

This is from the caption to the report’s frontispiece:

“Both harmful and beneficial effects.” The latter have now been expunged. Now we have this attitude, as I found searching for news of the Adonis blue:

The “climate crisis” is killing off the nice insects, and making sure that the horrible ones thrive.

Notes and References

The featured image, a drawing of the ant with an early caterpillar of a large blue comes from E. B. Ford’s 1945 Butterflies.

The greenhouse effect and terrestrial ecosystems of the UK. ITE research publication no. 4, 1990

Climate change and rare species in Britain. ITE research publication no. 8, 1994.

via Climate Scepticism

August 26, 2022 at 08:59AM

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