21-Aug The Web Weavers

Earlier, in the fourteenth century, Robert the Bruce was greatly impressed by the continual attempts of a spider to lay its first ‘bridge thread’. When it succeeded on its seventh attempt he was moved to keep on fighting the English, who he went on to defeat at the battle of Bannockburn.

Although London spiders are virtually all harmless, many people still possess an innate fear of them. This may not have been helped by the familiar nursery rhyme ‘Little Miss Muffet’, who is frightened by a spider and then runs away. Her father, Thomas Mouffet, was a London clergyman in the sixteenth century who was well known for trying to cure his sickly daughter by encouraging her to eat spiders – this being a common enough remedy at the time.

It is usually the half metre wide orb webs of the garden spider Araneus diadematus that we notice first in gardens. This spider is usually recognised immediately by its large size and markings. It is about as big as a small grape and has the distinct mark of a cross on its abdomen. Besides being one of the largest and most common of London’s spiders it is also one of the most variable in colour.

Individuals can be found in various shades of red, orange, yellow and brown. The female starts weaving her web by releasing a line of silk from her spinneret which gets caught by some slight air current and then gets attached to an obstacle nearby. Once firmly attached she then has her ‘spanning thread’ on which she can build her orb. From the middle of this first thread she then abseils down to create a Y-shape which forms the first three radii and central hub of her final orb. After this she goes on to lay down the rest of the radii or spokes of the web.

The almost identical angles between these spokes are all carefully measured with her legs. Once the radii are completed she then lays down the spiral with its equidistant drops of glue, taking care there is no glue in the centre where she will sit. As she constructs she regularly checks the tensions of various threads to ensure her web is both tight and vertical. Towards the end she outlines the web with ‘frame threads’ and lays a comfortable tangle of silk in the middle. Once complete, she may not decide to sit in the centre but retire to a lair nearby leaving one leg resting on a ‘signal thread’ which alerts her to the slightest vibration. From start to finish she may have released up to sixty metres of silk, with up to seven hundred attachments and travelled over forty five metres. In her short life she will repeat the whole process one hundred times or more.

If it is windy and something like a dried leaf gets caught in the web she is quite capable of cutting it out and mending the hole quickly. If a fly blunders in she moves even quicker, generally inflicting a lethal bite to the neck or the soft part of a leg in less than five seconds. Once her prey is paralysed she will then either wrap it up in silk for later or drag it to her lair to feed on its blood. However, if it is a wasp that gets caught she is far more careful, usually cutting it out to release it but, if it shows any sign of infirmity, she will kill it and then eat it instead.

Although the garden spider is the archetypal orb weaver there are many others in London in a wide variety of habitats. A close relation of the garden spider is A. quadrata whose orbs are often seen on gorse bushes. It is one of the heaviest British spiders weighing in at 2.5 g and is easily recognised by the four white spots on its abdomen placed in the shape of a rectangle. Sometimes the shape of the orb alone is enough to identify its builder. Zygiella x notata is called the Missing sector orb weaver as it appears to have left one small segment of its web unfinished. It has a preference for constructing its webs in window frames and then sitting in a lair nearby.

You can see its silvery abdomen if you tempt it out by tapping its signal thread lightly. Meta segmentata is probably the most common orb weaver in London. It makes a web with a distinctive hole in the middle. The female has a mark in the shape of a tuning folk on her upper side and a broad dark stripe when viewed from below. One or two males are sometimes seen waiting at the edge of her web for the most opportune moment to move forward. A close relation M. mengei is very difficult to tell apart in the field but does not lay a signal line to its web and so is always seen sitting in the centre of its orb.

The Walnut or Black orb weaver Nuctenea umbricata often makes webs on fences which it weaves at night, preferring to spend the day waiting for visitors under a piece of bark nearby. Its silk is tougher than most and so is often seen in tatters. If you see a small green spider on an orb web it is quite likely to be Araniella cucurbitina which makes a horizontal rather than a vertical web, sometimes right across the top of a flower. Gibbaranea gibbosa is one of many orb weavers which shows a preference for evergreens. It has two prominent tubercles which look like boils, making it easier than most to identify.

There is another family beside the Araneidae that make orbs. These are the Tetragnathidae or big jawed spiders. They tend to prefer wetter habitats and are best looked for near ponds and reedbeds. Besides their large jaws they are also known for their slim, often metallic-coloured bodies and outstretched legs when at rest. Their orbs often have small central holes and no signal lines and their webs are also often inclined to one side with less radii and spirals than is usual. Tegragnatha montana, the Large-jawed orb web spider is a typical member of the group preferring shady areas near water. It has a long body with wavy sides covered in a network of black lines. Two others relations, T.extensa and T. obtusa tend to be found near lakes or heather respectively. One last member of the group is Pachygnatha clercki which spins a very small web that is sometimes seen among leaf litter. It is a handsome spider as they go with a glossy abdomen punctuated with metallic markings. Twenty-five different orb web spiders can be found on Bookham common alone including all those mentioned here. The best areas to look are the damper sections of Central and Eastern woods, Eastern hollow and around the various ponds.