Wednesday 5 September 2012

How do spiders build their webs?


Garden Spider in web

So how do spiders do it?
I have been studying nature all my life and am still totally amazed by spiders. I am astounded by what they do. Their webs are a miracle I am sure you will agree?
There is a Garden Spider female with a web hanging over my balcony and I have wondered how she created it. The balcony is around 14 ft wide, and I know that having measured it, but somehow the spider has lines to both walls and another to the ceiling, as well as one to the balcony railings.
She is suspended in space with at least 6 ft between the one wall and the centre of her web. There is something like a 40 ft drop below into a car-park.

To weave a web

Apparently the spider puts out a line of silk that may be carried by the breeze to a nearby wall, trunk, twig, leaf or other solid surface. As soon as it hits the spider senses this and runs down it as well as creating another thread to make the connection stronger.
I have never seen this myself whilst observing spiders in the wild but have seen it captured on film in a presentation by David Attenborough so I know this is how it is done. It has been filmed in time-lapse and speeded up so we can view the process.
The spider creates other main lines below and to the side of the web and then starts filling in the rest of it around the central hub point. The spider uses as many as six different types of thread to create its work and there can be as much as 60 metres of thread in a single web. This is how the orb-weavers go about it and they make fantastic webs with intricate webbing and precision.
An orb-weaver can complete making a web within an hour after it has created the basic lines to hold it in place. Some orb-weavers make a new web every night.
Orb-web spiders make their webs under the cover of darkness for obvious reasons. They are a lot less likely to be seen moving about then, whereas in the daytime a hungry bird might spot them.
I love to see spider webs when they are covered in dew-drops. They look really magical glistening in the sunlight of an early morning, as if they weren't already magical enough!
In the UK there are lots of Garden Spiders about in late summer and early autumn. The females can be recognised by their larger size. They have a white cross on the back of their bodies too.
There are other types of webs including tunnel webs that do not appear so complex but the system of spinning a web is pretty miraculous I think even if some sorts of webs do not look as attractive to the human eye. And then there are spider types such as the Hunting Spiders, Crab Spiders and Wolf Spiders that do not build webs but rely on their hunting skills to catch their prey.

Tent-web spiders

In Tenerife where I am living we have a very common spider which is one of the tent-web spiders. Cyrtophora citricola tends to live in communities of males and females. They spin large sheet-like webs that they drape over foliage and hence the name "tent-web."

Tent-web Spider

The females spin cocoons in which they lay their eggs and these hang in the middle of their webs where they can stand guard over them.
This particular species, which is also found in the other Canary Islands and in Africa, tends to spin its webs in clumps of Prickly Pear cactus (Opuntia ficus-barbarica) and in the massive spiky leaves of the Century Plant (Agave americana). Living like this presumably offers the spiders some protection from predators and humans too! Many people are scared of spiders and kill them but I think they are amazing little animals!
Copyright © 2012 Steve Andrews. All Rights Reserved.

Wednesday 22 August 2012

Flowering Currant and Vapourer Moth and Magpie Moth caterpillars


Flowering Currant


I will always remember my visits to my grand parents’ house in Cardiff because their back garden had two very big Flowering Currant (Ribes sanguineum) bushes.  It wasn’t the pretty dark-pink flowers or even the strong resinous and fruity smell the leaves gave off if brushed against, though these were very enjoyable to see and smell that captured my attention, it was something that I could discover hiding in the foliage. It was the amazing caterpillars I could more or less guarantee finding on these bushes.

I would take a jam jar to capture some and take them home to keep so I could watch them as they changed first into pupae and later into adults. I was fascinated by all of this at an early age and still am! I used to learn about the species of insects I found by looking them up in good books on the subject.  I used to have the Observer’s Book of Larger British Moths.

Magpie Moth

The Magpie Moth (Abraxas grossulariata) is a beautiful species of moth with white wings dotted with black and yellow and a yellow body also marked with black. 



Magpie Moth

 It is in the Geometer moth family, or Geometridae,  and all species in this group have very cute “looper” or “inchworm” caterpillars that, as the name suggests, don’t crawl but make a loop out of their bodies as the pull the rear end up to catch up with the head section. They can stretch out in front of themselves as if they are testing or measuring what is ahead. Some types are camouflaged to look just like twigs and are almost impossible to see when they are completely still. Many types of caterpillar in this large family can also spin a long thread of silk if they are dislodged from where they are feeding. They can defy gravity by climbing back up these threads after all danger has gone.

The caterpillars of the Magpie Moth are a similar colour scheme to the adult moths and are mainly black and white like the Magpie bird the species is named after. They change into shiny black pupae striped with yellow. They are anchored loosely in a very flimsy cocoon that is almost non-existent and is made in dead leaves or tucked away somewhere on the bush the caterpillar fed on or near it.

The Magpie Moth was once a very common species though for some reason its numbers have declined drastically in recent years.  . This is somewhat surprising because it has a very wide range of food plants and besides the Flowering Currant can also feed on Gooseberry, Plum, Spindle, Hawthorn, Privet and many other shrubs and small trees. Maybe this decline is due to Climate Change because the caterpillars are the stage of this moth that has to survive the winter months.

Vapourer Moth

The second species of moth caterpillar I could often find on the Flowering Currant bushes was the Vapourer Moth (Orgyia antigua). This is a really weird insect because the females don’t look anything like a moth but more like a fat woodlouse. They have no wings apart from tiny stubs and cannot eat either. Basically they are a living bag of eggs and after mating with a male they lay their eggs and then die.
The male Vapourer Moths get a much better deal because they have normal wings which are coloured a rusty brown and they fly by day and night.

 Female Vapourer Moth

The caterpillars are really pretty creatures with dark greyish bodies covered with hairs and tufts of hair in yellow and blackish. The ones that will become female moths are much bigger than those that are the males. They pupate in a proper silk cocoon that they spin up somewhere on the bush or tree they are on. The female moths very often stay put after emerging and actually lay their eggs all over their old cocoons. They overwinter in this stage and hatch out in spring.


Vapourer Moth caterpillar

The Vapourer Moth is a very widely distributed species and can sometimes become a pest because its larvae can feed on a very wide range of plants, shrubs and trees besides the Flowering Currant.
Both species of moth gave me a lot of joy when I was a youngster and, as well as teaching me about the sometime very strange things that happen in the natural world, I learned how to look after them and see to their needs. Later that summer I was rewarded by seeing the adults hatch out.

Monday 23 July 2012

Ladybird Spiders need our help


Male Ladybird Spider (Eresus sandaliatus). Photo by Viridiflavus.

You have probably not even heard of the Ladybird Spider but this is hardly surprising because it is a very rare creature indeed.  Named after the brightly-coloured beetle everyone knows, the male Ladybird Spider (Eresus sandaliatus) has a vivid orange-red back with four larger black dots and two smaller spots on it.  If you saw one there wouldn’t be any chance of mistaking it for something else.
Well, actually there are many other species of spiders in the Eresus genus and several of these are known as Ladybird Spiders because of their colourful appearance. These spiders are collectively called “Velvet Spiders” because of the minute hairs that cover their bodies and legs.

Endangered species
In Britain the Ladybird Spider (E. sandaliatus) was so rare it was believed to be extinct until it was rediscovered in 1980 in a small population in Dorset. The species is listed in the British Red Data Book as “Endangered” and is, not surprisingly, protected under the 1981 Wildlife and Countryside Act.
In 1993, it was thought that there were only around 50 individual Ladybird Spiders still surviving in the UK, and that they were dying out mostly because of habitat destruction. In 2000, however, there was some very good news because more than 600 separate Ladybird Spiders were counted, and this number has been increased since then to 1,000 spiders.
Since 2000, other colonies have been successfully created on the Dorset heaths which are the sort of habitat the Ladybird Spider needs. Captive bred specimens of this very rare and but distinctive spider were released bringing the number of populations in Dorset from just one to eight.

Buglife – The Invertebrate Conservation Trust
Buglife - the InvertebrateConservation Trust, has started an important campaign to help ensure the safety and future survival of this very attractive but endangered spider.  The organization is collecting funds that will be spent on carrying on the captive breeding programme, establishing new populations of the Ladybird Spider, and monitoring the existing ones.
Buglife are accepting donations to assist in this vital conservation work but will reward those helping their efforts.  All those people who donate over £20 we will be sent a special Ladybird Spider pin badge, as well as an electronic newsletter  keeping them up to date on the progress of the project. Anyone who makes a generous donation of  £1000 or more will receive an exclusive invitation  to actually visit a site where you will be able to see the Ladybird Spider in its natural habitat.
Ladybird Spider lifecycle
The Ladybird Spider species sandaliatus is also found in Europe from southern Norway to the northern parts of Italy. They make their webs as tubes under the ground and mainly feed on small bettles and millipedes.
The smaller males become adults in early September, and overwinter in their webs.  They emerge from hibernation in spring and search for females in May or June of the following year. As well as being larger in size the female Ladybird Spiders are different in appearance to the males because they are a jet-black colour all over. After mating, female Ladybird Spiders lay between 35-80 eggs. After these hatch out, the baby spiders are fed with a liquid from their mother’s mouth. The female then dies and the spiderlings feed on her body. They stay in her web until the next spring when they leave to go and make their own.
The very similar and closely related Ladybird Spider E. cinnaberinus is also known as E. niger, but the males only have the four black spots and are missing the smaller ones. It is found throughout Europe and as far as the North Africa and La Gomera in the Canary Islands. It lives in underground tube-webs too in small colonies like its cousin and is also very rare.
I am sure you will agree with me that these Ladybird Spiders are fascinating creatures. If you would like to do something to help their survival in future then please get in touch with Buglife.

Copyright © 2012 Steve Andrews. All Rights Reserved.

Monday 16 July 2012

Chickweed is a common edible plant


Chickweed in flower

Chickweed (Stellaria media)  is a very common weed found growing in many places in the world, but whilst it is despised by gardeners, it is actually a delicious and nourishing edible wild plant. So instead of throwing it away or into the compost heap why not try saving some to use in the kitchen?
Chickweed is very common in the UK and many parts of Europe and likes to grow in cultivated ground and in damp soil. It self-seeds itself and easily forms large masses of its tiny green foliage. It is often found growing along paths and even in the cracks in concrete and paving stones.

Chickweed description

Chickweed is a fragile and straggling plant. It has small bright green leaves, and minute white, star-like flowers, with five deeply divided petals. It flowers throughout the year and often grows well in the autumn and winter months.
Chickweed forms mats of its green foliage and its branched stems reach about 40 cm in length, though they are mainly to be seen creeping over the ground.
It is an annual plant but quickly re-establishes itself from seed if it has died down due to dry conditions. Chickweed is native to the UK and Europe but is naturalised throughout the world. It likes to grow in nay reasonably moist soil in sun or partial shade.
The plant's Latin name Stellaria comes from "Stella", meaning a star, and referring to the shape of its flowers. It was called its English name of Chickweed because it was once much-used as a food for hens and other birds.

Chickweed's uses

Chickweed is a surprisingly enjoyable edible wild plant to eat. It is good in salads but also cooked as greens or added to soups.
Chickweed is also a medicinal herb with a number of uses in herbal medicine. Taken as an infusion it is a treatment for rheumatism. It can also be made into a poultice or an ointment and used as a remedy for eczema, skin irritation and other skin diseases.
Chickweed is rich in the minerals potassium and calcium, as well as being a source of vitamins A, B and C.
It is used in homeopathy to treat rheumatism, arthritis and bronchitis.

Chickweed recipes

The following recipe is taken from Richard Mabey's classic book for foragers -  Food For Free.
"Wash the sprigs well, and put in a saucepan without any additional water. Add a knob of butter, seasoning, and some chopped spring onions. Simmer gently for about 10 minutes, turning all the time."
Mabey  goes on to say that a dash of lemon juice or a sprinkling of grated nutmeg completes the dish, and that Chickweed cooked like this is very good served with rich meat.
Another recipe from Jessica Houdret's The Ultimate Book of Herbs & HerbGardening is as follows:
Chickweed and parsley dip
25g/1oz fresh chickweed, 25g/10z flat-leaved parsley, 225g fomage frais, 1 tbs mayonnaise, salt and freshly ground black pepper.
Rinse and pick over the chickweed, and chop it finely with the parsley. Put in a bowl with the other ingredients and mix well.
Serve as a dip with raw vegetables such as carrots, cucumber and red or green peppers.

Find out more about edible and medicinal plants that can be foraged for here.
Copyright © 2012 Steve Andrews. All Rights Reserved.


Saturday 14 July 2012

Arthritis worsened by Oxalic Acid in edible plants


Many people today suffer from arthritis and gout but what a lot of them don’t realise is that their painful condition is made worse by many commonly eaten foods and their acidic content. There are plenty of greens, vegetables and some fruits that contain oxalic acid and this is where the problem lies. Purines in foods become uric acid in the body. Even black tea is one such source of the problem. Cranberries can be good for you but they are a fruit with a high acid content. Moderation is the key with many such foods.

Margaret Hills
The late Margaret Hills, who had been a nurse, became famous for her book Curing Arthritis the Drug-Free Way, and a main part of her theory and the remedy she prescribed, is the avoidance of the foods and drinks that cause arthritic conditions. Hills had once suffered the painful ailment herself but had found a cure for it. 

Cider Vinegar
She claimed that apple cider vinegar counter-acted the problem by helping to break up the crystals in the joints. It contains malic acid, and this has an alkaline effect in the bloodstream. So, apple cider vinegar is a very important way of treating osteoarthritis and rheumatoid arthritis, according to Hills.

Hills helped many people cure their arthritis and soon had thousands of followers. She set up a clinic and also went on to write other books, all dealing with the subject of how to treat yourself if you suffer from arthritis and how to live a lifestyle that prevents the condition starting or returning if you once had it. She recommended eating a healthy diet that is low in purines and avoiding commonly eaten food such as citrus fruit and drinking black tea.

You see, the inflammation in the joints is caused by uric acid crystals that have accumulated over time. Oxalic acid and oxalates not only add to this problem but cut down the absorption of calcium, which is needed for the strength, repair and growth of bones. It is believed that oxalates, and calcium oxalate in particular, cause kidney stones.

Sir Ranulph Fiennes and Honeygar
Explorer Sir Ranulph Fiennes healed himself of terrible arthritis with cider vinegar in a product known as Honeygar, which also contains honey as its name suggests. He takes Honeygar daily and swears by its efficacy. His story was published in the Daily Mail in 2008 in a story by Matthew Dennison entitled: “Sir Ranulph Fiennes: I beat my arthritis with a vinegar cure passed down from my mother”.


Parsley Salad


Parsley
Amongst the plants that contain oxalic acid, Parsley (Petroselinum crispum) has large amounts of this substance in its leaves. Many people think of this herb as being healthy to eat, and whilst this is mainly true, because of the oxalic acid it should be eaten with caution by anyone with a tendency to suffer from arthritis.


Spinach leaves


Spinach
Many of us were brought up watching the Popeye the Sailor-man cartoons in which the hero of these animations derives all his strength from eating Spinach. Again, this plant is very good for us in moderation because os the vitamins and minerals it contains. However, Spinach (Spinacia oleracea) too has a lot of oxalic acid in it, as does its very close relative the Beetroot.  Beetroot and the Beets are all in the Beta genus of plants. Sea Beet or Wild Spinach, which is regarded an ancestor of the cultivated varieties, is Beta vulgaris. Chard too contains oxalic acid in its leaves and is actually a descendant of the wild plant just mentioned because it is known to botanists as B. vulgaris subsp. cicla.



Rhubarb on sale


Rhubarb
Rhubarb (Rheum rhabarbarum) may make delicious pies but the leaves of this vegetable are actually poisonous due to the acids in them. The pinkish-red stalks which we use in our cooking admittedly do not contain anywhere near as much oxalic acid but it is present. This has been known for a long time and many old books will include a caution that this food should be avoided or eaten in moderation by those who suffer from gout and arthritis.


Bermuda Buttercup


Sorrel
There are two sorts of plant known as Sorrel. First there are those in the Rumex genus including the Common Sorrel (R. acetosa) and the Sheep’s Sorrel (R. acetosella). They are known for having a sharp and tangy taste and make good additions to salads and can be cooked as greens. However the acidity of these Sorrels is caused by oxalic acid.
The second type of Sorrel that also contains high levels of this harmful acid are those in the Oxalis genus. Even their generic name tells you this is the case. Wood Sorrel (O. acetosella) and the Bermuda Buttercup (O. pes-caprae) are two of the many species. They all have pretty foliage like four-leaved clovers and many have dainty flowers too. The Oxalis species have a tangy taste and are eaten in salads but again the caution needs to be applied because of the oxalic acid they contain.

Purslane
The Common Purslane (Portulaca oleracea) is a common weed in many places in the world. This little plant with its semi-succulent leaves makes a popular and tangy addition to salads but again it has oxalic acid present in its leaves in the form of oxalates.  It can be cooked as well as eaten raw and has many other health-giving nutrients but care should be taken because of the oxalic acid present.

A useful list of edible plants and how much oxalic acid they contain is published here by the USDA:

Saturday 7 July 2012

Corn Salad or Lamb’s Lettuce


Lamb's Lettuce or Corn Salad


Corn Salad or Lamb’s Lettuce (Valerianella locusta) is an edible plant that, as its name aptly suggests, is good in salads.  Also known as Mache, it is a member of the Valerian family of Valerianaceae, and commonly grows as a weed in many places even though it is also widely cultivated.

Corn Salad can be found in waste ground, on hedge banks, sand dunes and on arable land used for growing other crops but usually in fairly dry soil. It will self-seed itself and spring up all over the place, even in cracks in a pavement and in walls.

It is a small annual plant that reaches a maximum of some 40cm and it bears really tiny pale lilac flowers. Corn Salad produces a rosette of spoon-shaped leaves and a short flowering stalk grows from this, usually producing flowers in spring. It is said that its name Lamb’s Lettuce comes from a similarity between the shape of its leaves with those of baby sheep

Corn Salad's range
Corn Salad is a very hardy plant and found growing wild in the UK, parts of Europe, North Africa and western Asia.  It has become naturalised in many parts of North America too after escaping cultivation there.
France is the main producer of Corn Salad today for sale to European consumers but it is also grown in Italy in Germany as a crop.  Germany, the UK and Spain are where the plant gets eaten the most in Europe. Organic Corn Salad seeds can be purchased online and from many suppliers of seeds.

Corn Salad can produce several crops in a year if cultivated. It is often grown as a second crop in August and September and gathered throughout the autumn and winter until it shoots upward to flower in spring. Although the whole plant is edible it is really only the leaves that are usually eaten.

Corn Salad can be eaten fresh on its own or mixed with other salad ingredients, and is particularly good with potato salad.  It has a pleasant tangy taste. Corn Salad can also be cooked a as green vegetable and served as a side-dish.

John Gerard's Herbal
Corn Salad was once foraged for by European peasants and was used as a food plant in Britain for many centuries. It was grown commercially in London from the late 18th century. Today it can be bought in seed form for cultivation as a salad plant. It was included in John Gerard’s Herbal in 1597, giving some indication of how long ago the plant was eaten. Because it grows in the autumn and winter, Corn Salad is a particularly useful plant to grow at these times in the year.
Drawing of Corn Salad

Vitamins and minerals
Corn Salad is a very healthy plant to eat because it is the source of several vitamins and minerals. It is said to contain three times as much Vitamin C as ordinary lettuce does. Corn Salad also contains Vitamin E, Vitamin B6, Vitamin B9, Beta-carotene , Omega-3 fatty acids, Potassium and Iron.

Corn Salad, although a small plant with very insignificant flowers, is well worth growing and eating.


Copyright © 2012 Steve Andrews. All Rights Reserved.

Wednesday 4 July 2012

Treacling for moths and moth books



Why moths fascinate me?
Since I was a little boy and discovered my first caterpillars, and found out how some types turn into moths that were like butterflies but different, I have been fascinated by the insects. It saddens me to know that many species are becoming much less in numbers in the modern world. Many people don't seem to know or care.


But moths are not only amazing creatures to see and study but are an essential part of the eco-system. They are the food of bats and many other nocturnal animals and their caterpillars become the food of countless birds, small mammals, reptiles and amphibians and other insects. If they are missing from the environment then other creatures go hungry.

The Moths of the British Isles
I recently went to visit my father in Cardiff and picked up some old and treasured books of mine. The Moths of the British Isles (Series I and II) by Richard South F.E.S. are, in my opinion, some of the best reference books on the insects available.


I say this because many a modern book only has a small selection of the more common or large and brightly-coloured species. However, these old books have all the small ones and the dull brown and grey species and even the types that were exceedingly rare many years back. There are quite a good selection of books on moths though.


Moth names
I love the names that moths have. Here is a selection: the Lunar Spotted Pinion, the Old Lady, the Lobster Moth, the Puss Moth, the Hummingbird Hawk Moth, the Chocolate Tip, the Argent and Sable, the Frosted Green, the Wood Tiger, the Vapourer, the Kentish Glory, the Emperor, the Rosy Footman, the Neglected Rustic, the Clifden Nonpareil, the Alchymist, the Rannoch Sprawler, the Brighton Wainscot, the Nonconformist, the Ruddy Highflyer, the Toadflax Pug, the Belted Beauty, the Essex Emerald and the Gold Spot.
They sound more like titles for plays or detective novels, some form of confectionery, public houses or maybe a rock band even! Anything but a flying insect!
Caterpillars
When I was a child and later in life too I used to delight in rearing caterpillars in jars and other containers and make sure they had the leaves they needed of their food plants. When it was time for them to pupate some types needed soil to burrow in and others needed leaves or other material to fashion into cocoons. It was all a part of the learning process for me finding out about all these requirements.

Pale Tussock Moth caterpillar or Hop Dog


Some types of moth only pupate for a few weeks or months but others must go through the whole winter and spring before they emerge. Waiting patiently for the day they hatched out was always worth it when I watched the beautiful creatures drying their wings with all their colours fresh and radiant.
There are many ways of finding caterpillars too. One good way is to beat bushes and overhanging foliage with a stick or to shake it onto a tray of some sort below.
Some caterpillars are very unusual looking creatures and very beautiful in their own way. The caterpillar of the Pale Tussock Moth, or "Hop Dog" as it is also known, is a good example, covered as it is in coloured tufts of hair against a lime green background.
Some types fall off and curl up or start crawling and others like some of the "looper" caterpillars can hang down on threads if they are dislodged.
Hawk Moths
Some caterpillars can be spotted by looking out for the areas of foliage they have eaten. Big caterpillars like those of the Hawk Moths do this.
Finding moths at night is exciting too because you never know what you might discover. There are various ways. You can search around lights in outhouses and buildings where theinsects are attracted, or looking on flowering shrubs like the Butterfly Bush (Buddleia davidii) is another great way of finding moths as they feed on the nectar.
Speaking of moths that are feeding, a very good way of tempting the insects is by an old-fashioned method known as "sugaring" or "treacling." To do this you make up a mixture of treacle and sugar and maybe a dash of some alcoholic drink and daub it in strips on walls and fences and tree trunks and then come back an hour or so later with a torch to see what is there.
On a good night it will tempt all sorts of species but not only moths. I remember getting the attention of a policeman when I was a boy so, if you try sugaring, be careful where you put your sticky treacle lure because it might not just be moths that it attracts.
Copyright © 2012 Steve Andrews. All Rights Reserved.