Garden spiders enjoy a good summer

There is every indication that the garden spiders, hanging head down and motionless in the centre of their orb-webs, have had a good summer. I am not alone in noting just how many there seem to be around this autumn, the topic forming on the lips of many a conversation over recent weeks. From the patio I can count a dozen or more webs, each with the corpulent form of a female garden spider, Araneus diadematus, at its centre. Each of these females has reached maturity and will have gone through eight moults, shedding the patterned exoskeleton to grow in size. The smaller males, which sit separately within their own triangular webs, undergo fewer moults.

The garden spider is a common and widespread species, found across Britain and within a range of habitats beyond the gardens with which it is most often associated. A closer examination reveals bold patterning and a white cross, carried on her back. The presence of the cross made this spider an object of veneration during the Middle Ages and may be one reason why this is the spider that features most often in book illustrations.

As with many other spiders courtship is a rather dangerous affair for the males, each of which has to convince the female whose web he has entered that he is a suitor and not a meal. The male approaches the female with great caution, playing the threads of her web to signal his approach. More often than not the female will lurch towards the male, prompting him to let go of her web and drop away, his fall broken by the safety line that he will have anchored to the edge of her web. After several attempts the male will either have successfully tamed and mated with the female or been taken as prey. The female will remain in the web over the coming days, receiving more suitors, before leaving in October to lay her eggs nearby. These are protected with a dense covering of silk, slightly yellow in tone and with the appearance of cotton wool. Her work done, the female will remain beside the eggs. No longer feeding, her life ebbs slowly away and the cycle begins over again.

Spiders lose out to a special wasp

When you think of spiders, you tend to think of them as having things pretty much their own way. They are top dogs, the fearsome predators that snare, snatch and trap insects and other invertebrates. When it comes to web-producing spiders and flying insects it seems even more one-sided, the insects blundering into the web where they are quickly subdued.

Spiders do not have it all their own way though; there is, for example, a group of wasps that specialises in hunting spiders. Belonging to the family Pompilidae, these spider-hunting wasps are smart species, lightening quick in flight and easily overlooked (despite their size). The wasps favour open ground, with short vegetation and areas of bare sand in which they can excavate a nest. These wasps do not form complex social nests like our more familiar yellow and black vespids, but are solitary in habits. The female hunts spiders, paralysing her prey with her sting and then delivering it back to a prepared burrow into which she will lay a single egg. Each nest chamber (or cell) will contain the egg and one paralysed spider, the latter providing a meal for the wasp larva that will soon emerge from the former.

This group of wasps contains 43 species nationally but, even with such a small number to get to grips with, they represent a serious challenge for the entomologist. Knowledge of their favoured habitats means that finding them is not that difficult. Their quicksilver movements, however, make them particularly hard to catch. Once in the net they have the tendency to sting (from experience I can tell you that it feels like a white hot needle and makes your finger joints ache) and once in a glass tube they can still be exceedingly difficult to identify. Fortunately, some of the more common species can be identified fairly readily, through a combination of body and leg colour plus structural features and wing venation.

One of the first of these wasps that I ever encountered was a species called Episyron rufipes (like many less familiar insects, these wasps lack a common name). It is widely distributed but favours heathland and coastal dunes. Active mainly from June through into August, it targets orb-web spiders (but will also take wolf spiders). Once it has paralysed a spider, Episyron will store it temporarily on a plant while the nest is dug, before retrieving it. Watch a suitable patch of sand and you might be lucky enough to see it deliver the spider to the newly excavated nest. That the orb-web spiders don’t have things all their own way makes me see them in a slightly different light; now they are victim as well as villain.

We are not alone

I watch her some mornings as she moves across the wall; her eight, stiletto-tipped legs find unseen purchase on the plaster, gravity-defying and assured in their hold on this world that exists in a vertical plane. Her body is just a few millimetres in length, darkly patterned and with an arc of tiny glistening eyes on the top of her head. I have not worked out which of our many spider species she is, in part because I do not wish to disturb her daily routine.

She is not alone, as other spiders lurk in the corners of this old house. Some are rarely seen and I suspect that they indulge in nocturnal scurryings long after we have turned in for the night. Others are chance encounters, seen briefly as they race across the carpet and dash under the sofa; big hairy beasts that spook our rather feeble hounds. Then there are the daddy-long-legs spiders, Pholcus phalangioides, that hang in untidy webs where wall meets ceiling. These fragile looking spiders gyrate their bodies if disturbed, the motion so fast that the spider becomes little more than a pale blur, an effective and surprising defence for something so small.

Despite the ungainly appearance Pholcus will tackle other spiders, including those from outside that have ventured into the house in late autumn. Any that touch her web are approached and it is then that the long legs come into play. They give her greater reach, allowing silk drawn from the spinnerets to be flung over another spider with minimal risk. As well as other spiders, Pholcus will tackle small moths and mosquitoes, both unwelcome visitors to many homes, and I sometimes spot the body of a White-shouldered House Moth, partly wrapped in her silk.

One of the reasons why this house is so popular with these spiders is its age, lacking the dry warmth of modern houses, with their central heating and double-glazing. Like other house spiders, Pholcus can survive long periods without water but even she must descend to find it from time to time. Her eggs are thought to be prone to desiccation and presumably cannot cope in a modern house.

I do not mind sharing our house in this way. Most of these other residents are innocuous enough and have little or no impact on our lives. The occasional visitor may go away with the impression that we are a little untidy, perhaps, but the scatter of webs and their delicate residents provides a sense of connection during these bleak winter months. We are sheltering together from the elements outside, a community of lives whose daily routines sometimes bring us into contact with one another.

Simple skills of a silken kind

It is on these damp autumnal mornings that the architectural skills of our many and varied spider species can be best appreciated. While bits of wall display simple webs, the gaps between plants support the more-skilled constructions of orb-web spiders belonging to the genus Araneus. Undoubtedly the most familiar of these is the Garden Orb-Web Spider Araneus diadematus, delicately-marked with greys and browns and with a white cross on her back. It was this cross that saw her venerated widely during the Middle Ages and which provides a useful means of identification.

Dew-covered webs provide an opportunity for you to view the web’s construction, revealing the fine threads typically formed by the spider during the previous night. The Garden Orb-web produces a sizeable web, with a defined central hub of meshed thread. Outside of this there is a narrow spiral, known as the strengthening spiral, which circles six or seven times around the hub. Radiating out from the centre are two or three dozen threads which stretch out to the stout outer frame. It is to these radiating threads that the main spiral of threads is attached, the spiral beginning a little way out from the central hub. This leaves a gap, known as the free zone, between the strengthening spiral and the main body of the web itself. The main spiral is the key to securing a meal, since the spiralling threads are studded with blobs of glue. Flying insects unfortunate enough to encounter the web are held fast, affording the spider the opportunity to seize the prey and deliver a venomous bite. Some prey are deemed too large or too dangerous to be tackled, for example wasps, and the spider simply cuts them free rather than risk injury.

Sometimes the spider will sit motionless, head down in the centre of her web, her eight legs alert to the vibrations caused by an insect caught in the web. At other times she will tuck herself away on the edge of the web and use a signal thread, which runs from her hiding place to the centre of the web, to detect prey. That the spider can move across the web with impunity, not becoming caught in her own sticky trap, comes down to her use of the non-sticky radial threads when moving about the web. She also makes use of special oily secretions which cover her legs and reduce the chances of her becoming stuck.

These webs are particularly important to the female orb-web spiders, as they need to secure food in order to complete their series of moults and to produce the hundreds of eggs which will be deposited nearby at the appropriate time.

Home-grown spider

I watch her some mornings as she moves across the wall; her eight, stiletto-tipped legs find unseen purchase on the plaster, gravity-defying and assured in their hold on this world that exists in a vertical plane. Her body is just a few millimetres in length, darkly patterned and with an arc of tiny glistening eyes on the top of her head. I have not worked out which of our many spider species she is, in part because I do not wish to disturb her daily routine.

She is not alone, as other spiders lurk in the corners of this old house. Some are rarely seen and I suspect that they indulge in nocturnal scurryings long after we have turned in for the night. Others are chance encounters, seen briefly as they race across the carpet and dash under the sofa; big hairy beasts that spook our rather feeble hounds. Then there are the daddy-long-legs spiders, Pholcus phalangioides, that hang in untidy webs where wall meets ceiling. These fragile looking spiders gyrate their bodies if disturbed, the motion so fast that the spider becomes little more than a pale blur, an effective and surprising defence for something so small.

Despite the ungainly appearance Pholcus will tackle other spiders, including those from outside that have ventured into the house in late autumn. Any that touch her web are approached and it is then that the long legs come into play. They give her greater reach, allowing silk drawn from the spinnerets to be flung over another spider with minimal risk. As well as other spiders, Pholcus will tackle small moths and mosquitoes, both unwelcome visitors to many homes, and I sometimes spot the body of a White-shouldered House Moth, partly wrapped in her silk.

One of the reasons why this house is so popular with these spiders is its age, lacking the dry warmth of modern houses, with their central heating and double-glazing. Like other house spiders, Pholcus can survive long periods without water but even she must descend to find it from time to time. Her eggs are thought to be prone to desiccation and presumably cannot cope in a modern house.

I do not mind sharing our house in this way. Most of these other residents are innocuous enough and have little or no impact on our lives. The occasional visitor may go away with the impression that we are a little untidy, perhaps, but the scatter of webs and their delicate residents provides a sense of connection during these bleak winter months. We are sheltering together from the elements outside, a community of lives whose daily routines sometimes bring us into contact with one another.

Orb webs adorn the garden

This is the time of the year when orb web spiders are at their most obvious. Several have cast their beautiful spiral webs across the corners of our windows, with others strung between the branches of garden shrubs or across the door of the greenhouse. In the centre of each web sits a female spider, Araneus diadematus, the familiar Garden Orb Web Spider, head down and motionless. On the rare occasions when the web appears empty, the telltale signal thread running from the centre of the web to a suitable nook in the brickwork soon reveals her location. Should an insect become caught in her web she will rush down the signal thread, take up a position in the centre of the web to determine where the victim is caught and then dash along the appropriate radial thread to deliver a fatal bite.

The patterning on the back of the female resembles a white cross and this may explain why this particular spider was the object of veneration during the Middle Ages. By now, in early September, she will have completed eight moults, shedding her exoskeleton to grow in size and reaching just over a centimetre in body length. The smaller male, who will be travelling around in search of a mate, undergoes just six moults. Understandably, the smaller males make a careful approach to any suitable female, the risk of being eaten increasing as the season progresses. The male very gradually moves forward onto the female’s web, attaching a safety line that will allow him to drop rapidly from the web should the female lunge at him. Each time the female attacks, so the male has to begin all over again, the process tedious to all but the most patient observer.

The male makes his courtship all the more complicated by the fact that he seeks to lure the female onto a special mating thread. If he succeeds in getting her onto the thread then she will signal her compliance by hanging motionless, head down. This affords the male the opportunity to insert one of his palps into her reproductive organ; the other palp, however, requires yet more of the gradual and patient courtship. After mating, at some time during September or October, the female will leave the web to lay her eggs somewhere close by. The eggs, which are held together in a tight solid mass, may number up to eight hundred and are collectively wrapped in rough silk, sometimes camouflaged with small bits of debris. By now the female will be close to death; emaciated she takes up a position next to her egg sac, where she will remain over the last few weeks of her life.

Encounter with a spitting spider

As soon as I saw her I was pretty sure of her identity; Scytodes thoracica, the spitting spider. Once she was safely sealed in the confines of one of my specimen tubes I checked her identity against a guide and took in her spiderly beauty. Very pale brown in colour, Scytodes is delicately marked with a deeper brown through a succession of spots on her thorax and strongly domed carapace, and bands on her thin legs.

The large, domed carapace is a striking feature and houses a pair of enormous double-lobed glands. The front lobe of each produces poison while the larger rear lobe produces a sticky, glue-like substance. Each gland is linked by a duct to the front of the fang where it emerges through a small opening. By using muscular contractions to compress the gland, the spider is able to ‘fire’ a stream of poisonous glue at its intended victim, easily covering a distance of 10mm or more. At the same time, the spider very rapidly moves its fangs from side to side, creating a zig-zag of deadly spray that quickly immobilises its prey; only then does the spider approach more closely and deliver the coup de grace. If there is any sign of a struggle on the part of the victim, Scytodes will deliver the bite to one of the extremities before retreating and playing her patient game.

As its weaponry might suggest, this is an active hunter which does not bother to build a web, but instead stalks prey with a slow and steady gait. Scytodes is synanthropic in habits, which means that she lives alongside us in our houses and offices. Although widely distributed within southern Britain, south of a line from the Humber to Glamorgan, this spider is either somewhat uncommon or poorly reported. I have only seen her twice in the 10 years that I have lived in this old house and I do not recall seeing her in any of the other houses in which I have lived. This house is quite old and seems to support a good number of spider species. The spider’s powers of dispersal may be rather poor, since it’s young do not disperse on the breeze, so dispersal is likely to be through the movement of household objects from one location to another. Another factor that may restrict the species to low levels of abundance is the length of time (some three years) that it takes the females to reach maturity. We tend to think of insects, spiders and other invertebrates as being short-lived, ephemeral creatures but this is not always the case. Having secured her identity I released her, in the hope that she remains unnoticed by my wife!

The deadly hermit

Living in an old house means that I live alongside spiders; from the delicate daddy-long-legged forms that hang in the upper corners of rooms to the scuttling species of Tegenaria that race across the floor at the end of summer. I also encounter spiders when I am out and about looking for beetles and it may be this that has increased my interest in these much-maligned creatures.

Although we lack any truly threatening species, there are a number of spiders found here that are seriously impressive, their bulky forms and large fangs sufficient to menace the casual observer. One of these is Atypus affinis – sometimes called the purse web spider – a primitive species that is closely related to the trap-door and bird-eating spiders that one often sees in television documentaries. Atypus is a scarce spider (there is just one Norfolk record) but it is widely distributed across the southern half of Britain. One reason for its scarcity may be its requirement for undisturbed grassland and heathland habitats; another may simply be that it is easily overlooked due to its largely subterranean habits.

Atypus lives a hermitic existence, cocooned for much of her life in a sealed silken tube within a burrow excavated in the soil. The silken tube can be up to 39 cm in length but is more usually 20 cm or so long, with about a third of the tube showing above ground. This ‘above ground’ portion of the tube is camouflaged with grains of sand and other debris and can easily be mistaken for a piece of old root. The spider waits within her silken tube until some insect wanders across its surface; then she strikes, her huge fangs puncturing the silk and stabbing into the victim. The fangs hold the victim in place, pinning it to the web and, once subdued, the spider disengages one of her fangs, using tiny teeth on the base of her chelicera (the basal part of the jaw to which the fang is attached) to saw through the silk, opening up a slit through which the victim can be drawn into the cocoon. Once inside, the spider takes her meal to the base of her burrow before returning to repair the slit, ready for the next unfortunate insect to wander by.

During the winter months the spider will effectively hibernate at the base of the burrow, the upper section of the web shrinking back to become even more root-like. Come spring and the top section has to be rebuilt, a process that may be carried out annually for the seven or so years of life that a fortunate Atypus may enjoy. As the great scholar of spiders, W. S. Bristow, noted ‘this is a spider of distinction’.

Winter insects hard to find

The winter months offer reduced opportunities for those of us interested in insects and other small creatures. Many species will sit out the cold conditions by burrowing under bark, burying themselves within the leaf litter or by squeezing into a nice dry crack in the brickwork. However, there are still insects and arachnids to be found at this time of the year.

Clearing away dead plant material from one of my borders the other day revealed several caterpillars, overwintering in this form before changing and emerging next year as adult moths. One of the ones I recognised was the caterpillar of the angle shades, a delightful moth that has featured at my moth trap during the summer months. Just below the surface of the soil, as I forked it through, was the large brown pupal case of a hawkmoth. Over two inches in length, it was almost identical to one that I had found last autumn. I managed to overwinter that one in the shed and on 5th June this year an adult privet hawkmoth emerged to be photographed and released. Other moths are still on the wing, including small brown ones that appear at lighted windows late in the evening. These are male winter moths, a species that is unwelcome in those gardens with fruit trees. Broad bands of sticky material can sometimes be seen wrapped around the trunks of fruit trees. These have been fixed there by gardeners, in an effort to trap the almost flightless female winter moth as she attempts to crawl up the trunk to lay her eggs. There are even moths on the wing in the house. Aptly named the white-shouldered house moth, these tiny moths appear on the curtains or at my reading light on most evenings.

There are other small creatures in the house, including two-spotted ladybirds that have hunkered down for the winter, pressed up against the corner of a window frame. A daddy-long-legs spider has taken up residence on the ceiling of the dining room. This spider has long legs and a cylindrical body and, if disturbed, will vibrate its web rapidly – a useful defence against potential predators. Another species of spider remains very much in evidence in the garden. This large spider has taken up residence on my larch-lap fencing. Known by its Latin name of Nuctenea umbratica, the females of this species are rather impressive. Reminiscent of a garden spider, but darker and with a flattened body, Nuctenea spends the day concealed in a crack. Once darkness falls, the spider emerges to wait for prey. Each panel of the fence seems to support seven or eight of these spiders, seemingly forming a healthy population and just one of the species to add interest during winter.