Arthropedia - Dark Days

Making the most of winter

December is a dark time in Norfolk for an entomologist with most insect life tucked away in dormancy, whether as an egg awaiting spring to hatch, a larva or a hibernating adult. It is pretty hard to find anything out and about in the garden other than the odd fly or two when it is sunny.

Traditionally, this time of year was when specimen collections were pored over, re-ordered, and records were laboriously written up. Nowadays, we look back through digital photographs, trying to identify for the umpteenth time that tantalising blurred image. Records from notebooks are put into spreadsheets, reliving warmer, sunnier days, in preparation for sending to the county recorders. But what the entomologist wants most is life, new life, especially in the shape of a new species before the year is out, to add to the garden or site list or, better yet, the Life List.

A cluster of woodlice under a stone. These are mostly Common Shiny Woodlice with two Common Striped and one Common Rough. A dreary winter can be enlivened by searching for these engaging little creatures and finding out just how many species inhabit your garden. The commonest species are collectively known as the ‘Famous Five’. It is said that a site that is good for invertebrates should have the entire Famous Five plus one, with plus two being even better. I am pleased to say that our garden is a ‘plus two’ site.

In past years, the dark days of winter have led me down perilous paths, away from my beloved insects. One year I spent several cold days rummaging through leaf litter, under blocks of wood and old bricks and delving into the compost bin all to find the ‘Famous Five’ commonest species of woodlouse that I had neglected to ensure were present in the garden. I am happy to say that they are all present and correct. Another winter was occupied by tracking down and trying to identify any millipedes and centipedes that were lurking in the garden – the paving slabs have been wonky (or ‘on the huh’ as we say in these parts) ever since.

Centipedes, Cryptops hortensis — Centipedes rushing for cover as a paving slab is lifted. These are *Cryptops hortensis*.

A Lithobius sp. centipede — A *Lithobius* sp. centipede. This one was actually rescued from the pond and was put on a piece of wood in the sun to dry out.

A Spotted Snake Millipede (*Blaniulus guttulatus*) and two *Ophiodesmus albonanus* millipedes found under a stone. Millipedes are easily told apart from centipedes by having two pairs of legs on most of their body segments whereas centipedes only ever have one pair per segment.

But last winter, and again this one, I have well and truly gone over to the dark side (according to my hymenoptera-fancying friends who think my interests should stay firmly allied to the bees). For I have taken a fancy to the silk spinners and web weavers and found myself a whole new world of life to be fascinated with. I have finally taken the plunge and started looking at spiders. They’ve always been there, in the garden and the house along with everywhere else and I have noticed them, drawing and photographing them, putting names to a few and logging them in the garden record diary. I have all the books to identify them and even a microscope but they’ve always felt beyond my capabilities as an amateur naturalist. But by concentrating on just the ones in the garden, I have gradually been honing my spider identification skills one spider at a time. And it has paid off. I can recognise quite a few families now and know who the garden regulars are so if something new turns up I may not know what it is but I do know that it’s worth a closer look.

Shine A Light

This time of year there aren’t many spiders obviously about but there are signs of occupation in the form of cobwebs on the fence, the eaves of the shed, on the greenhouse frame and around windows. A torch-lit stroll of an evening reveals the inhabitants. Mostly these are the Missing-sector Orb-weavers (Zygiella x-notata), so-named after the missing bit in their web where the signal thread (the thread that leads from the web’s hub to the spider’s retreat where it spends the daylight hours) runs through.

My favourite is Nuctenea umbratica, the Walnut Orb-weaver. We have a huge female living on the fence by the gate. She is completely hidden during the day but in the evening she slowly emerges from her hideaway, stealthily coming out one leg at a time until she is fully exposed in her shining polished glory.

A careful search usually reveals a Steatoda nobilis or an S. bipunctata, the latter often lurking in the dark recesses of the shed. It is sometimes known as the rabbit-hutch spider, a hint of where to look for one! The lace-web spider Amaurobius similis is also rather fond of the shed, females occasionally setting up home in the deep tread of an old wellyboot, but thay are also to be found on the fence. On a short length of fence (covering 2-3 panels) I counted three Amaurobius, one each of both Steatoda species, a Nuctenea, a wandering male Metellina sp. and at least 12 Zygiella.

*Amaurobius similis* making a home underneath a wellyboot in the deep tread.

A torch-lit *Zygiella x-notata* on the fence.

A mature male *Steatoda nobilis* showing his ‘boxing-glove’ pedipalps.

Expect The Unexpected

These are all pretty common species in the garden but I do sometimes turn up something out of the ordinary too. I was counting the number of Pholcus phalangioides hanging from the ceiling in the stairwell (10!) when I spotted a small speck of ‘muck’ by the light fitting. I carefully reached up with a specimen pot and nudged it in – low and behold it was a spider, which I had an inkling that it was going to be. And a rather strange looking one at that. It had a knobbly looking abdomen and under closer inspection I could see pronounced bumps or tubercles on it, making it a species of Ero. There are four species of Ero in Britain, two with one pair of tubercles on the abdomen and two bearing two pairs. The species with just the one pair are both fairly widespread and common (we have found one, Ero cambridgei, on our nearby allotment) in Norfolk but the other two are not. I counted the tubercles – two pairs – I was looking at my first Ero aphana or E. tuberculata! Well, not quite, as I had recently found one in my local cemetery but it was a first for the garden (or house anyway). Unfortunately, as with the cemetery specimen, this one was an immature so I couldn’t determine exactly which of the two species it was. Hopefully I will find it again, or another, when it is mature and I can then tell which it is.

Sketches of Ero sp. — Sketches of *Ero* sp., viewed down a microscope.

Ero aphana or E. tuberculata — *Ero aphana/tuberculata* found on an ivy leaf in my local cemetery.

Ero under the microscope — The same *Ero* under the microscope clearly showing the four tubercles on the abdomen. The enlarged but as yet undeveloped pedipalps show it to be a sub-adult male.

The Ero spiders are called pirate spiders in Britain. Instead of building their own web to snare prey in, they seek out the webs of other spiders and pluck the silk strands, pretending to be prey themselves. When the occupant of the web rushes out to get its dinner, the Ero quickly grabs and bites, paralysing it. Then simply, and literally, sucks the life out of it, usually through a small hole in a leg. The Ero spiders have relatively long legs to tackle other spiders and the front two pairs are armed with long spines to help grab hold.

Spider, Ero sp. — The *Ero* from our house, being somewhat unco-operative.

Morning Glory

Strangely, a lot of invertebrates turn up right by the kitchen door – sometimes on the wall but often on top of a wheelie bin or the lid of the compost bucket. I think this is because the side of the house acts a bit like a wind tunnel – creatures get blown down and alight on the first thing they come across or seek shelter in the lea of the building. I often find something of interest when I poke my head out the door in the morning, on the way to top up the bird feeders first thing. Any speck on the pale yellow render is given a second look and I generally have a specimen tube at the ready in my pocket. In winter I don’t find so much so was very pleased to spot a little crab spider – an Ozyptila species.

Ozyptila crab spider — A speck of ‘muck’ on the wall turned out to be a delightful little *Ozyptila* crab spider.

These are lovely little spiders with a rather ‘crusty’ appearance, often covered in debris, usually in the form of tiny particles of soil. There are 10 species in Britain, most of which are found at ground level amongst stones and leaf litter although at night they are often found climbing up plant stems. They are very slow moving and are very good at playing dead so are easily overlooked. Ozyptila praticola is probably the commonest species and we have had them in the garden a few times. I have always found them on the wall of the house, usually round the back by the conservatory, and about two or three feet above the ground. Perhaps they were caught out by the dawn during their nocturnal wanderings and decided not to travel back down in case they were spotted by an eagle-eyed Robin or Wren who would snaffle them up in a heartbeat. Staying immobile is probably the safer option.

But back to the one by the kitchen door. Duly potted-up and popped under the microscope, I was expecting to see the tell-tale dark pattern on the sternum that would make it O. praticola but it wasn’t apparent. It was also greyer looking than previous specimens and had a white edge to the carapace rather than a reddish-brown one. The legs were a plain yellowy-brown, lacking the darker annulataions (rings) of praticola. Viewing the underside of the abdomen I was pleased to see that it was a mature female with an obvious epigyne so in theory I should be able to identify it. But it was a pretty small spider and I couldn’t be sure so I posted images on the UK Spiders Facebook page for help. Ozyptila sanctuaria was suggested as a possibility.

Ozyptila spider — The crusty-looking, debris covered *Ozyptila*.

Ozyptila underside showing the epigyne. — Underside showing the epigyne.

Armed with this knowledge I looked again down the microscope and at the sketches I had made of the structure – sometimes it is better to draw the epigyne before you look at the diagrams in the field guide so you really are drawing what you see and not what you hope to see! Still unsure, I swapped the lenses in the microscope to the higher magnification ones I had recently bought and turned up the brightness of the external lighting set (another recent purchase made with spiders in mind). Luckily the spider was extremely co-operative and I finally managed to get the angle and illumination just right in order to properly see and sketch those important female parts. And yes, it was Ozyptila sanctuaria, rather a good addition to the garden list and for the Norfolk Spider record database. Hats off to the people on the UK Spider Group!

Sketches and studies of *Ozyptila sanctuaria* in pencil and pen and ink.

Dick Jones in his book ‘Spiders of Britain and Northern Europe’ (published by Country Life) gives a nice introduction to the Ozyptila genus. He outlines the mating behaviour thus: when the male approaches the female she adopts a submissive pose with her forelegs folded in front of her head. The male climbs on her and walks over her, casting a fine silk net (called a bridal veil), seemingly tying her down. He then crawls beneath the female and mates with her. Once the male has departed, the female simply shrugs off his ‘net’, easily escaping her silken nuptial bonds.

For more information on spiders, I recommend the British Arachnological Society website. This has several useful factsheets, including Essential Spider Info (Fact Sheet 1), which includes terminology such as ‘pedipalps’ and ‘epigyne’.