Monday, March 23, 2009

Early Grey moth (Xylocampa areola) and Dark Chestnut (Conistra ligula)

I am an amateur naturalist trying to discover everything that lives in my garden.

I promise that shortly I will end my minor obsession with moth postings dear readers and return to describing some of my garden's other life. For now however, two more moths caught in my new home-built moth trap.

Photo 1 shows an Early Grey (Xylocampa areola), its wings camouflaged to help it hide on trees and, photo 2, a rather tired and tattered looking moth that I think may be a Dark Chestnut (Conistra ligula) though is possibly a Chestnut (Conistra vaccinii) (My identifications come with a ‘health warning’ - I’m no moth expert and happy to be corrected). You can find better photo's on the excellent UK Moth site.

Caterpillars of the Early Grey feed on Honeysuckle, and those of the Dark Chestnut on Willow and other plants.

I learn from my copy of Moths (Michael Majerus) that the Dark Chestnut is an unusually early egg-layer amongst British moths, usually laying in March.

Sadly, beyond the facts above, I’ve been able to find very little to say about the life-styles and behaviours of either of my moths. Of course, this may be because I’ve not searched enough. If there is one thing that I have learnt from writing this blog however, it won't be because there is nothing remarkable to discover about them. As I've discovered time and again during my researches, there is an almost inexhaustible subtly and complexity in nature.

Take for example, the two butterflies, The Grayling (Eumenis semele) and the European Silver Washed Fritillary (Argynnis paphia) -

In his semi-autobiographical Curious Naturalists, a wonderfully readable account of a life spent watching and recording behaviour in birds and insects, and one of my all-time favourite natural history books incidentally, the Nobel Prize winning biologist Niko Tinbergen described some of the 50,000(!) experiments he and his team performed to gain an understanding of the behaviour of the former butterfly.

During the breeding season, male Graylings are in the habit of chasing almost anything that flutters by in the hope it may be a female. Using equipment no more sophisticated than a fishing rod 'baited' with a series of cut-out paper shapes, Tinbergen was able to reveal such facts as i) Although male Graylings are sensitive to colour (they preferentially feed on blue and yellow flowers) surprisingly, when choosing to give chase, they don't care about the colour the object fluttering by ii) Nor are they the least concerned that the ‘flutterer’ should resemble a fellow butterfly – they will happily chase a fluttering paper rectangle iii) They do care about size however; If you’re a male Grayling seeking a mate then, within reason, the bigger she is the better!

This is only the start. Once a male finally meets a female, a rich and complex courtship ‘dance’ ensues with he performing acts such as wafting scent over his partner with his wings, and gently clasping her antennae between them.

Now, in her book, Courtship: A Zoological Study (publ. Heinemann), Dr. Margaret Bastock describes some similar studies (made by D. Magnus in the 1950's) into the breeding rituals of the Silver Fritillary. Again males will chase a variety of passing ‘fluttery things’, but this time males are choosy about colour -they like best to chase yellow things.

Two butterflies, two rich and complex behaviours with intriguing differences, both only ‘decoded’ by thousands of hours of patient observation. It makes me wonder what intricate shenanigans my two moths may be about in the dead of night. (Anyone?).

Even supposing more is known about my two moths however, with more than 850 larger moths in the UK alone, not to mention 250 hoverflies, more than 450 spiders, 3200 Ichneumenoid wasps…and let’s not even think about beetles (see here), it’s certain that only a tiny fraction of what goes on in the gardens, fields and forests on our doorsteps is known in any detail.

Personally I find it both an inspirational ‘call to arms’ to we amateur naturalists to get out our notebooks and our ‘paper butterfly' experiments, but also (if you’ll permit me a slightly gloomy ending to today’s posting) a little sad to think that in one’s lifetime there will never be enough time to observe even a small part of what there is.

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