Thursday, November 3, 2011

Silverfish




If you have a cupboard under the stairs, or kitchen cupboards that have dark, damp corners, then the chances are that you also have some of these silverfish Lepisma saccharina  lurking in them.  These primitive wingless insects belong to an order known as the Thysanura and are often thought of as being living fossils, having first evolved over 300 million years ago. They are covered with silvery scales that are easily detached and they also move fast, which makes them difficult to capture intact; this one has lost part of one of its three tail appendages and also the tip of an antenna. They are most active at night, emerging to feed on whatever organic material  they can find - spilled food, paper, even the glue from cardboard cartons. Sometimes they find their way into baths in bathrooms.


Although silverfish are present in most houses they don’t often produce severe infestations because the females only lay about twenty eggs during their lifetime, hidden in crevices until they hatch. They are, apparently, easy to maintain in captivity and will live for up to five years on a diet of damp paper and a pinch of flour, with regular access to moisture.


The first detailed description we have of a silverfish was recorded in Robert Hooke’s Micrographia or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries thereupon, published in 1665. 



The book contains this copper engraving of the insect, which is of stunning accuracy when you consider that Hooke observed it with lenses that he ground himself for his simple microscope – modern microscopists still marvel at his extraordinary skill and powers of observation. (You can see another example of his skill here).

Samuel Pepys was also mightily impressed and bought a copy of the book on publication, noting in his famous diary on 20th.January 1665took home Hook’s book of microscopy, a most excellent piece’.

Hooke called the silverfish ‘the small silver-colour’d bookworm’ and described, in his elegant prose, how ‘it appears to the naked eye, a small glittering Pearl-coloured Moth, which upon the removal of Books and Papers in the Summer, is often observ’d very nimbly to scud, and pack away to some lurking cranney, where it may the better protect it self from any appearing danger. Its head appears big and blunt, and its body tapers from it towards the tail, smaller and smaller, being shap’d almost like a carret’.

He described how it had ‘ conical body, divided into fourteen several partitions, being the appearance of so many shells, or shields that cover the whole body, every of these shells are again cover’d or tiled over with a multitude of thin transparent scales, which, from the multiplicity of their reflecting surfaces, make the whole animal appear a perfect Pearl-colour’ 



You can find pictures and information on the firebrat - the silverfish's larger but less common cousin - here and you can also view some other animals that share our houses with us here and here.

14 comments:

  1. Fascinating Phil. I remember seeing these a lot when I was a kid; usually in the bath.
    I haven't seen any in a long time now.

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  2. Wonderful! I am after those, but I have been unable to find one in years. Maybe I should give the pantry a clean up and see if I come across one. Beautiful photos and what a lovely book Microcraphia is. If you click on it, you will be hooked for hours (pun not intended).

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  3. Thank God, it is only 20 eggs a year! Silverfish have made inroads into the old books which belonged to my great-grandfather,I keep dried neem leaves with the books now.

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  4. Goodness, I haven't seen any since I was a child in Wales.

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  5. Thanks Phil - I've seen silverfish - I may even have a photo somewhere - but I didn't know anything about Hooke's 1665 work.

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  6. Hi Phil, I remember seeing a few of these 'scudding' around the cupboards in Fishbourne.
    Hooke was born on the IoW. There's a display about him at the planetarium in Yarmouth, where I noted he invented the universal joint. You'd be the one to tell us if his mechanical inventions may've been inspired by articulations among the Arthropoda - did nature get there first with the universal joint?

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  7. I sometimes wonder how small creatures like this eventually find their way in to new homes.

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  8. Hi Keith, I wonder if there are fewer because our houses and better insulated, warmerand drier that they used to be?

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  9. Hi Blackbird, I bought a Dover reprint of Micrographia in a secondhand bookshop years ago - one of the best six quids I ever spent. It has a wonderful foldout inside the back cover of Hooke's masterpiece flea engraving...

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  10. Hi lotusleaf, I've read about the wonderful insecticidal properties of neem - sounds like an incredibly useful plant...

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  11. I certainly don't see as many as I used to Toffeeapple...

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  12. Hi John, Micrographia is a really fascinating book - well worth delving into - I'm sure its downloadable from the web somewhere..

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  13. Didn't know he came from the IoW Rob. Not sure about universal joints but nature certainly invented the rotary engine (flagellum)

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  14. A lot seem to come in at this time of year John - we've got a rising population of spiders at the moment!

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