Wednesday, November 14, 2007

Common Nettle Capsid Liocoris tripustulatis

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

In my previous posting I described some of my garden's nettles, and it was on such that I discovered the little bug seen in the centre of photo 1 (click to enlarge). If you look closely you'll see a second individual a little lower down the nettle stem.

Photo 2 shows a magnified (40x) image of my bug. I can only speculate over what purpose it serves the bug to wear the rather smart, yellow, arrow-symbol on its back.
I had expected to struggle, and quite possibly fail, to identify my little insect, but the internet is an amazing thing! Ten minutes of searching against 'bug', 'nettle' and suchlike and I'm reasonably confident to pronounce my insect The Common Nettle Capsid Liocoris tripustulatis.

L. tripustulatis is a member of the insect family the miridae. From my copy of Insects of Britain and Northern Europe (M. Chinery, Collins) I learn that the miridea family is, in turn, part of the insect order hemiptera or the so-called true bugs. The true bugs have piercing mouthparts for sucking the juices of plants and can be distinguished from the beetles, by beetles having hardened wing cases ('elytra') that meet at a line along their backs without overlapping (see a previous posting here).

There are about 6000 true bugs in the family meridae. About 200 are found in Britain.

The true bugs are equipped with a drinking straw' (rostrum) for tapping the stems of plants and sucking out the juices. This is carried horizontally below the body and can be clearly seem in the 40x magnified image of photo 3 (click to enlarge).

Although I've come across various general discussions on the true bugs, I've been able to discover almost nothing on the specific habits of L.tripustulatis; A search of Google books turned up The Biology of the Plant Bugs (Wheeler and Southwood, Cornell University Press). The publishers have made a selection of pages available online and from a single sentence I learn that, along with their association with nettles, L.tripustulatis is known to need on nectar from buttercups. In addition, from a single sentence in my copy of Insects on Nettles (B.N.K. Davis, Richmond Publishing) it seems L.tripustulatis undergoes at least five larval instar phases. Aside from these facts however, the habits of my little bug remain a mystery to me. I'd love to know a little more. As I learnt from my readings on hoverflies, there are simply so many insects that often even the basic behaviours of many are completely unrecorded. My failure to find any substantial information on the natural history of L.tripustulatis perhaps indicates a good project for a keen amateur out there. On the other hand, perhaps much is already known and I've simply not looked in the right places. If anyone out there can help I'd be pleased to discover more about my handsome little capsid.

Monday, November 12, 2007

Stinging nettle Urtica dioica

I am an amateur naturalist trying to learn a little about all the life in my garden.
In a quiet corner of my garden (at (1.8,2.0) - see here) I have been carefully cultivating (hem, hem) a patch of stinging nettles Urtica dioica (photo's 1 and 2 - click to enlarge).

I have two books in my possession that have enabled me to learn something about this ubiquitous British weed: my trusty copy of The Englishman's Flora (Geoffrey Grigson, Paladin) and secondly a recently acquired copy of Insects on Nettles (B.N.K. Davis, Richmond Publishing).

From Geoffrey Grigson's book I learn alternative names for the stinging nettle include The Devil's Leaf in Somerset and Naughty Man's Plaything (!) in Sussex. Secondly that nettles were unintentionally imported into the States by the settlers, with John Josselyn recording in 1672

"[nettles] have sprung up since the English planted and kept cattle in New England"

and thirdly that the Scots poet Thomas Campbell (1777-1844) wrote about sleeping in sheets made from the fibres of nettle stems (I would love to think there is someone out there reading this blog who still has a set of nettle bedsheets. If you're that slumberer do please leave a comment!)

From Dr.Davis' book I am learn that the botanical name dioica is derived from the Greek di-oikos -"two houses" - a reference to the fact that nettles have separate male and female plants which can be differentiated by the flowers: bright yellow on male plants and "silvery, furry" on females. Nettles clearly have a dubious reputation as a weed; Seen under the microscope however I have to say I find the flowers really rather beautiful. Photo 3 shows my 40x closeup of what I assume to be a female plant.

Nettle leaves are edible after suitable cooking (blanching in boiling water for example) and I can report that I myself have eaten nettle risotto from my garden's crop: my memory is of it tasting vaguely like a cross between watercress and spinach.

Of course, the unpleasantly familiar attribute of nettles is their sting. Photo 4 shows my (100x) image of one of the vicious hypodermic syringes responsible. It seems there is some dispute over exactly what chemical is to blame for the painful sting with hystamines, formic acid and oxalic acids all being variously implicated. Hope is at hand however: From Dr. Davis' fascinating book above I learn that one nettle variant (var. subinermis) common in Cambridgeshire lacks stinging hairs.

Nettles get a mention by Shakespeare no fewer than nine times, my favourite being

"the strawberry grows best underneath the nettle,
and wholesome berries thrive and ripen best
Neighboured by fruit of baser quality" (Henry V, Act 1)

Does anyone know if there is any truth in this suggestion that strawberries grow well in the proximity of nettles?

And finally, for all of us who've suffered the stings of nettles. I learn that things could be much worse: from Wikipedia's entry on nettles I learn that Urtica ferox, a dioica relative native to New Zealand, has a sting powerful enough to kill a horse! Can anyone out there report living to tell the tale of having been stung by this terrible triffid?