Sunday, July 29, 2007

Scarlet Tiger Moth Panaxia dominula

I am an amateur naturalist on a mission to blog everything living in my garden.
Having blogged my first butterfly in my previous posting, it seems only fair that today's posting should feature an example of the butterflys' close cousins, the moths. Photo 1 (click to enlarge) shows a Scarlet Tiger moth, Callimorpha (formerly Panaxia) dominula. I photographed it in my garden at (0,2) (see here) enjoying one of this summer's rare moments of sunshine.

Scarlet tiger's give the lie to the commonly held belief that :

i) moths only fly at night (Scarlet tiger's are active during the day),


ii) moths are the drab, unattractive cousins of butterflies. Not true here, I'm sure you'll agree! Furthermore, what my camera exposure hasn't well captured is the attractive yellow colour of certain of the wing spots. Also, had I succeeded in photographing my moth in flight you'd have seen the wonderful bright red underwings (just a thin section are visible in the photo).

The caterpillars of Scarlet Tiger's are black and orange with spiky hairs . I haven't yet found any in my garden but there's a nice photo on Ian Kimber's UK Moths site. They are fond of nettle and dead nettle, but especially comfrey.

It is a fascinating feature of so many of the garden creatures I am discovering through this blog, that they are interesting not only to an amateur such as myself, but that their forms and behaviours also present a challenge to the very best theories of the professionals. A reminder that no one need travel to exotic jungles to discover something new in nature: the back garden is far enough!

In the case of the Scarlet Tiger a challenge to the professionals seems to be to understand the existence of a number of Scarlet Tiger sub-species with slightly differing wing-spot patterns in terms of genetic- and evolutionary theory. If you're like me, the details are hard to follow, but you can get a flavour of the discussion from online scientific papers such as those here, here and here. The first of these, by Fisher and Ford, also includes pictures of the various wing patterns. The debate seems to be over whether the separate subspecies of Scarlet Tiger are a consequence of natural selection or a consequence of so-called "genetic drift" (i.e. that the natural world is such a complex place that there's always the opportunity for species to vary and survive by simple luck and happenstance). Or at least that's my extremely limited understanding of things. Maybe someone more expert can provide a better explanation?

As a resident, a particularly nice thing for me to discover from skimming the papers above was that Oxfordshire is the place to be for Scarlet Tiger moth study! The population of Scarlet Tiger's at Oxfordshire's Cothill Fen Nature reserve has been rigorously recorded and studied for almost sixty years. I live about 10miles from Cothill. I just wonder... before it found its way into my garden, was my moth was having his particulars noted down, ready for publication in some learned scientific journal ?!

Saturday, July 28, 2007

The Peacock Butterfly Inachis io

I am an amateur naturalist on a mission to identify and blog all the life in my garden.
It has been the wettest UK summer on record with the river Thames breaching its banks and flooding parts of Oxfordshire.

Despite the incessant rain I am pleased to still be seeing plenty of insect life in my garden. The Peacock butterfly (Inachis Io) in photo 1 (click to enlarge) was amongst a flutter ( the collective noun for butterflies I believe) of half-a-dozen feeding on the flowers at the front of my garden (at (1.5,0.5) - see here).

Peacock butterflies can live a surprisingly long time (11months according to this site) and hibernate over winter from September/October. The outer surface of the wings is dark brown, providing camouflage for the butterfly when it's hibernating in dark places such as holes in trees and garden sheds.

The striking feature of the Peacock butterfly are of course the eyespots on the wings. Scientific studies have shown that these have a powerful deterrent 'fear' effect against predatory birds such as blue tits.

Something I found remarkable is that along with their eyespot defense, Peacocks can emit a hissing sound when attacked. They achieve this by rubbing together structures in their forewings. According to the paper above, these sounds apparently have little effect on birds, but other studies have shown that clicks emitted in the ultrasonic have a deterrent effect on predatory bats.

I read here that happily Peacock butterflies have enjoyed a healthy expansion of their populaton in recent decades. Numbers in Finland have more than doubled in the past twenty-five years. The distribution map on this site shows that Peacocks are essentially ubiquitous in Britain, save for the far North of Scotland.

Finally, regular readers of this site will know that I am fond of generating images using my hobbyists microscope. To get microscopic images of my Peacock would have meant killing it - something I wasn't prepared to do. As it happens however, when I originally bought my microscope I also bought some pre-prepared slides of butterfly 'parts'. I don't know to what species they belong (is anyone out there expert enough to know from the image alone?), but for no other reason than its beauty and fascination-value, photo 2 (click to enlarge) shows a 100x image of a butterfly proboscis - the 'drinking straw' mouthpiece through which a butterfly sucks up nectar. As a non-butterfly expert, I was a little puzzled by the presence of two tubes in my microscope slide. My understanding is that a probscis is indeed formed from two tubes however, but that normally these are 'zipped together' shortly after an adult butterfly emerges from its cocoon. I wonder whether this implies that my microscope slide was prepared from a young butterfly - or maybe there's another explanation? And as a final snippet of information, in preparing this posting I came across a paper by Rusterholz and Erhardt (Ecological Etomology,22, 1997) explaining that given a choice over what to dip their proboscis into, Peacock butterflies prefer sucrose sugars over fructose, and fructose sugars over glucose - so now you know!

Saturday, July 21, 2007

A mushroom Conocybe siliginea

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

Growing on my lawn (at (1.0,1.0), see here) I found the little mushroom seen in photo 1. It's about 5cm tall with a 1.5cm diameter cap.

Unlike many of the natural history topics I'm encountering as part of my self-imposed project to identify the living things in my garden, I come to the fungi armed with a (very) little prior knowledge. Unfortunately, what my past studies have mostly taught me is that little white/brown mushrooms can be very difficult to identify! There are hundreds of species that match the description "small and whitish" and putting a name to one can be tricky, even for the experts.

Let's assume however, that you're an amateur determined to try to make progress. Where do you start? Firstly its essential you compile a detailed list of the fine features of your mushroom. Is the stem smooth or, as here (you'll need to click on the photo to enlarge) minutely powdery ('pruinose')? What colour are the gills? Do they contact the stem and run some way down it, or, as for my mushroom, are they essentially free of it? Does the flesh bruise a different colour when touched? (It didn't). And so on.

Next, its essential you take a spore print. Don't be put off - this is extremely easy to do. Simply place the cap of your mushroom, gills down, onto a sheet of paper or microscope slide, wait a while, remove and you'll find the surface has accumulated a fine dusting of spores (photo 2). Spore colour - white, black, brown (as here) or otherwise - is an extremely useful feature during identification. All good guide books include it in their descriptions.

Under a microscope incidentally, you really get an impression of just how prolific a producer of spores a mushroom really is. According to my copy of Fungi (Spooner and Roberts, Collins New Naturalist) a mushroom such as the common field mushroom (Agaricus campestris) may produce up to forty million spores an hour! Photo 3 shows a 100x close up of part of the thirty-minutes of spore production responsible for the spore print in photo 2.

Clearly you need to pick your mushroom to take a spore print. Within reason however, and provided you don't set out to decimate an area or pick especially rare species (see the list on the Fungus Conservation Forum website), this may be considered acceptable. Mushrooms themselves are basically fruit bodies. The main body of a fungus exists as a network of microscopic mycelial threads running through the soil. Picking a mushroom is analogous to picking an apple from a tree therefore (a tree with its branches running below ground and fruits popping up through the soil).

With a list of naked-eye features and a spore print, you may now be able to identify your mushroom. Unfortunately, for many species this is still not enough and further progress requires the use of a microscope (one with with a 1000x oil immersion lens).

Armed with such you can see features like those of photo 4. The blurry brown mass lower right is the edge of a gill. The brown, oval objects are spores. Spore shape and size (measured here as about 13.5um x 8.5um) varies between species and is another helpful feature for identification.

Yet another feature can be seen in photo 4 by clicking to enlarge and looking below the number '5' on the graticule. I believe (though here I am reaching the limits of my own expertise) the semi-transparent 'club shaped' entity seen there is an example of a cheilocystidium. Cheilocystidia are specialised cells that decorate the edges of the gills. Amazingly, it seems that no one really knows what they're for, but their shape and size can be yet another important diagnostic feature in your efforts to identify your mushroom.

And finally, coming back to my mushroom, what does the combination of creamy-white bell-shaped cap, cinnamon-brown gills and spore print, a fragile, pruinose stem, 13.5x8.5um oval spores and club-shaped cheilocystidia lead me to conclude about its identity ? Answer: growing on my lawn I have Conocybe siliginea...err, or possibly rickenii...or tenera...As I said, little white mushrooms are tricky!

...or possibly Concybe subovalis, which having had a few more appear on my lawn in recent days, and from the photos here, may be a good candidate.

A budgie (Melopsittacus undulatus)

I am an amateur naturalist trying to identify all the life in my garden.

No, it's not a spoof (!) a white budgerigar really has turned up on the bird-feeders in my garden. I have no idea where it came from. Since the rules of my project state that I'll blog all the life in my garden however, it's only fair that it gets a posting.

My feathered friend has been hanging around my and my neighbour's garden for about a week now. As you can see he is remarkably tame and I was able to approach within a few feet to take the photo, left (click to enlarge).

From Wikipedia's article I learn that budgerigar's are small parrots of the genus Melopsittacus indigenous to Australia. The word itself is thought to derive from the Aboriginal budgerigar meaning good eating (!)...don't worry, I didn't!

On the basis of my budgie having a blue cere (the 'faceplate' containing the nostrils), I understand he's a male (the ceres of females being white or pale brown).

I'd like to think he will, but frankly I don't give my budgie much chance of surviving the British winter in the wild. If you're from the Oxfordshire area therefore and are missing a white budgie, do please leave a comment!

A Hoverfly Sphaerophoria scripta

I am an amateur naturalist trying to learn a little about everything that lives in my garden.

On the basis that you cannot have too much of a good thing: another photo of a hoverfly! (Click on it to enlarge).

Using the beautiful colour plates in my copy of Hoverflies (Francis S. Gilbert, Richmond Publishing Co.), I'm identifying this one as a male Sphaerophoria scripta, males being longer and thinner than the females. Once again, I've failed to find a common name (anyone?).

Apparently, nine species occur in the genus Sphaerophoria in Britain. I believe the continuous yellow stripe on the side of my hoverfly's thorax (the body section after the head) indicates he's a member of the species scripta however (unless someone can tell me otherwise).

From what I've gathered about the diet of hoverflies (see here) I'm guessing mine here is enjoying his lunch of pollen or nectar. In their larval stage S.scripta eat aphids. I'd like to know what an S.scripta aphid looks like, but have not managed to find a photo though this site has extensive images and details on hoverflies as well as countless other insects.

I read that for most hoverflies mating takes only a few seconds. For S. scripta however, mating can take several hours with the male riding on the female's back in flight. Can anyone comment on what advantage S.scripta gets from being different?

As I mentioned at the end of my last posting, whether hoverflies engage in courtship rituals, and if so what form the ritual takes is, it seems, largely unknown - a good project for the patient amateur observer!