Winter active spiders in the house

We are having an exceptionally mild winter and, although much of the time it is wet and dull, winter invertebrates respond to the prevailing conditions. While some spiders overwinter in the safely of an egg sac, or as tiny spiderlings on leaf litter and tree trunks, others winter as grown young or adults. In warm conditions, some of these species overwintering as grown spiders continue to be active through the winter months, hunting or looking for mates. This post was prompted by a silky, silvery mouse spider Scotophaeus, that I found on the kitchen ceiling in the morning (above). So, I decided to investigate which other spiders were about inside and outside of the house. All the photos taken this morning.

Pholcus phalangioides.

The Pholcus spiders in my outside toilet, which is not heated, have been much more active than it is usual in winter. Pholcus adopts a curious flat position in cold conditions, but a large individual has been changing corners and looks gravid, or indeed very well fed.

Amaurobius similis with centipede prey

 In a crack at the bottom of the toilet door lives an Amaurobius similis. A couple of weeks ago I watched as a large springtail, Orchesella villosa, tripped one of her woolly silk lines. The spider sprung out like lightning out of her retreat, but the springtail, making use of its wonderful jumping abilities, escaped unharmed. Today the spider was luckier. I noticed she was out, which is unusual, and looking closer I saw she was busy with prey: a centipede, likely Cryptops hortensis.
What other spiders are out and about?
Inside the kitchen window, a mid-size garden orb-weaver Araneus diadematus, hung from her web. They occasionally wander inside and live on small plant midges or drosophila from the fruit bowl. Females have occasionally reached full size inside the house and attracted males.

A poor shot of an Araneus diadematus inside the house.

Zygiella x-notata legs visible touching its web.

On the sheltered top corners of windowsills you might find Zygiella x-notata, the missing sector spider, in a silky retreat, often next of her egg sacs and the empty wrapping, one of her front legs touching the guide thread to the center of her web. At night she comes out and sits in the middle of her web. They are active regardless the weather, building their new webs early in the morning even in hard frost.

Spiders in glasshouses

Today at work, I had the chance of inspecting some glasshouses in the Thwaite Botanical Gardens of the University of Hull. They are heated glasshouses holding cacti, succulents, ferns and other plants from around the world. I was pleasingly surprised by the diversity of spiders in them. I found a single Woodlouse Spider, Dysdera crocata, under a bin (above). Quite fitting as we were collecting woodlouse for a practical on woodlouse diversity. The students were quite impressed!
 The first surprise was to find several Walnut Orb Weavers, Nuctenea umbratica. We dislodged an individual from a tree growing in a pot and it proceeded to play dead, legs drawn in, as they do when disturbed. They are usually nocturnal, spending the day in a crack in bark, but this large female I found later was sitting in the middle of her web, I wonder if the reason is it was a very dark, overcast day. There were many more smaller sized individuals, also sitting out in their webs, and it is quite likely this spider matures on her second year of age.

Mature female Nuctenea umbratica.

A student pointed this female Tegenaria to me, she found under a tarpaulin.

A mature, gravid Araneus diadematus sitting on her web.

This was the second nice surprise. One of the glasshouses held a healthy population of Garden Centre spiders, Uloborus plumipes.

By the toilets, a number of Pholcus phalangioides.

Where there are windows, there are window-frame spiders, Zygiella x-notata. 

I found a single Ero sp. egg sac. These spiders abandon their characteristic egg sacs, and they are not the easiest to find.

On a window ledged, a female Araneus diadematus looking like it has seen better days. Its abdomen shrivelled. Her days are counted after she lays her eggs and weaves her egg sac.

Araneidae: typical orb weavers

It's #arachtober, a whole month dedicated to the celebration of spider awesomeness and diversity! For this reason, I will be writing a daily post on the natural history of a British spider family.

For the first post, I have chosen Araneidae, the typical orb weavers. This is one of the largest spider families and include many familiar species, such as the garden spider (Araneus diadematus), the window frame spider, Zygiella X-notata, the wasp spider Argiope bruennichi, and the small cucumber spider Araniella sp. There are 33 species in the UK.  The drawing on the left shows the eye arrangement in the family (based on a photograph by Kiron Basu)

In foggy weather, orb webs become very visible, heavy with dew. The spider is sitting in the central hub.

A. diadematus spinning its web.

The spider's web
The most characteristic feature of araneids is that they spin flat, rounded webs with radial threads connected by a spiral net-like pattern of threads, which they attach to vegetation or other structures  The threads are sticky, and able to trap flying insects. The spider either sits in the middle of the web (often at night) or hides in a retreat on a corner of the web, with one of their legs touching a signal thread connected to the hub of the web, which allows them to detect the vibrations produced by any struggling insects. Orb spiders often eat their web at the end of the day, and build a new one in the morning. As they adopt a sit and wait strategy to catch prey it is easy to find particular individuals in the same spot every day.

Dangerously close. The male (on the left) was dispatched before he had the chance to mate, after a lengthy and careful approach.

Mating and cannibalism
Adult females are readily distinguished by their larger size and swollen abdomen. Females often cannibalise males (often right during mating), and males might die after mating a couple of times so at the end of the season, only mature females might remain.

Female Araneus diadematus with its fresh egg sac.  Once their egg sac is finished, the female sits on it and will die in a few days.

Egg sacs and spiderlings
Females lay their eggs, often over a thousand of them, and spin an egg sac around them. Females might die shortly after egg laying. The spiderlings hatch, moult inside the egg sac and then they emerge. In some species, like the garden spider, they spin a communal web and cluster together in it until they are ready to disperse.

A spiderling ball, newly born A. diadematus

At the end of the summer, full size Araneus diadematus can subdue quite large insects such as droneflies, butterflies and wasps.

A. diadematus are very variable in background colour with a range from sandy to chocolate brown, although the white markings on the abdomen tend to be more uniform.

A glimpse of Zygiella mating

 By chance while in the garden a couple of days ago, I spotted two small spiders near each other, which immediately attracted my attention. The smaller spider, which I could now see it was a male, proceeded to approach the passive female and insert one of his palps in her epigyne. After a few seconds, he retreated and repeated the process with the other palp. The translucent inflated palp is just visible in the photo above, where the female is on the right. A gust of wind separated the spiders and, despite the male's apparent efforts to find her partner, thus ended their affair. The female now rested atop a flower stem and I could watch and identify her by the pale leaf pattern on her back and ringed legs: a missing sector orb web spider, Zygiella x-notata.
 Given how slow spider courtship may be, in particular the slow initial male's approach to an often aggressive female, I count myself lucky to have witnessed the mating of yet another spider in the garden.

The female Zygiella x-notata

Christmas spider

A large volume of search keywords hitting BugBlog are about spiders. "Scary spider" in particular features high on the search keyword ranking. I hope the blog helps dispel the myth of spiders as scary bugs. I thought fitting to finish 2011 with a not very scary spider, one that most of the time is hiding outside on the corner of windows, doors and railings in a little silky retreat, and that weaves a fresh web every morning all through the winter. Zygiella x-notata, the Missing sector spider, or window-frame spider, makes characteristic webs with a missing section, though which its signal threat runs (top left hand corner). This one's web glistened on the sun today, with the backdrop of cotoneaster berries that the blackbirds haven't quite finished yet.

Twelve bugs of Christmas

Today we woke up to a mild, sunny day and I was pleasantly surprised by the diversity of active bugs about. I made a count of species and when I got to twelve I was reminded of the traditional carol and made up a buggy version:

12 ladybirds walking | 11 winter-gnats dancing |10 honeybees buzzing |9 bluebottles basking | 8 leafhoppers leaping | 7 woodlice hiding | 6 hoverflies flying | 5 snails sleeping | 4 spiders weaving | 3 harlequins | 2 drone flies | and a bumblebee on ivy

The honeybees in the local wildlife garden were coming out tripping over each other and ladybirds (7 spots mostly but also harlequins and 22 spots) were awaken by the mild temperature. I counted 5 spider species outside (Tegenaria, Zygiella, Pholcus, Steatoda, Linyphia). The main surprise was the bumblebee worker, extremely fast and active and with pollen baskets full with pollen.

Here is a slideshow of bugs seen and photographed today

Foggy morning

The fog painted the spider webs hanging from bushes and fences this morning with pearly dew drops. It made evident that at least three spider species are still active. On the photo an Araneus diadematus web, we also saw Zygiella x notata and Linyphia triangularis webs.

Window frame spider

Zygiella spinning its web on a garden railing

Suddenly, most of the summer bugs seem to have disappeared to leave your usual autumn suspects: wasps, a few Bombus pascuorum, garden spiders and plenty of flies. There is a common bug, though, that hangs on year round. It is the window frame spider, Zygiella x-notata. This species is an orb spider (related to the Garden Spider, Araneus diadematus) which spins its webs on gates, window frames, wheelie bins and other flat surfaces associated to human constructions. The web is quite recognisable, as it has a sector with no connecting threads in it, it is thought to be adapted to be built in such flat dimensions by keeping the signal thread free from getting tangled in the sticky connecting threads. The signal thread runs in the middle of this sector and allows the spider to detect any vibrations due to insects trapped in it. During the day, the spider hides in a silky tube on a corner, with the first pair of legs touching the signal thread that leads to its web. At night she is often seen either just outside the retreat or on the web, in a more similar way to garden spiders.

A Zygiella x-notata web on a garden gate. The spider's retreat is on the top right-hand corner. Note the signal thread and the 'empty' segment on the orb

This one used to live inside the kitchen window.

Eventually, she laid her eggs and spun a cocoon for them. She sat on the cocoon until she died.