Garden Centre Spider

Bugblog has curled under a dry leaf and enjoyed an extended period of dormancy. The new year has brought some interesting invertebrates so I foresee some blog activity in the next few days. In a trip to the garden centre, a little spider dangled from the ceiling. Something called my attention: its front legs. They were long and robust, and adorned with dark tufts of hairs. The spider held them forward, using them as feelers as it moved. It reminded me of an orb web spider, but not one I had seen before, so I posted a photo on Twitter asking for help. Within minutes, Chris @BHWWildlifeGdn answered:

@aBugBlog uloborus plumipes? commonly known as the garden centre spider
— Chris (@BHWildlifeGdn) January 19, 2015

A close up of the spider in my hand, to give you a sense of scale

And so it was! This species has been expanding in the UK since the early 90s, when it was found in garden Centres in Reading, Liverpool and Southampton. In fact, it is not even mentioned in my spider field guides. Now it is widespread through most of England and large cities in Scotland, where it is almost exclusively found in or around heated greenhouses of garden centres, and is thought to have come with plants from Holland, where it was also found. The original distributions appears to be Africa and the Mediterranean, although it is expanding worldwide thanks to its ability to thrive in garden centres.
 Uloborids are cribellate spiders, they brush their silk with a comb-like set of bristles in their rear legs making the silk sticky. This silk is so efficient immobilising prey that uloborids have lost their venom glands, not that this makes much of a difference to us, as this species is so small its fangs will be unlikely to break the skin.
 I shall keep an eye for this unusual spider every time I visit a garden centre. It builds horizontal orb webs (although it is not a member of Araneae, but of Uloboridae) and sits underneath, resembling a fragment of dead leaf and their egg sacs are white and of an unusual shape too. Chris recommended looking around the lights.

More information
Page for Uloborus plumipes at the Spider and Harvestman recording scheme. Here.
Wikipedia page.

Another girdled snail

I spotted this Girdled Snail, Hygromia cinctella, the second ever I have seen, climbing up a wall in my street a couple of days ago. The white whashed wall made a white background for it and I was pleased to get to photograph the live snail as it went about its business.

Alien Invaders

Today I saw the first Harlequin ladybirds of the year. Two individuals adjusting their position in a railing to catch the winter sun. In September 2006, I came across a beautiful, but strange, ladybird. Yellow, large and with 21 spots, I had never seen anything like it, and it wasn't in the insect guide I checked at home. A few weeks later, I found a large black ladybird with black spots. I had a little plastic container with me and took the insect home to photograph it. This time I took a bit more time to identify it. It was a Harlequin, a non-native ladybird species that since 2004 it has rapidly spread across the UK. The Harlequin is native from Asia, and has been widely used as pest control in greenhouses, from where it has escaped. The species had spread invasively in the USA and mainland Europe, from where it invaded the UK.
 This ladybird is unique in that it shows a large variation in color patterns between individuals. The following photos, all taken in Hull, illustrate this.

There was already a very well organized survey to follow the spread of this species in the UK, the Harlequin Ladybird Survey, and I reported these sightings. Data sent by members of the public (in the form of records and photographs) have helped to follow this invasion in great detail. This series of maps from the survey's website show the spread of the Harlequin in the UK year on year.
There is lots of info from the website, not only on the Harlequin, but also on the native ladybirds. You should be able to identify not only the adult ladybird, but also the larva. Here you can compare it with a 7-spot larvae.

Harlequin ladybird larva (with two lines of reddish spiky tufts on top of abdomen).

A 7-spot ladybird larvae (only black tufts on top of abdomen). Tufts are not obviously spiky.

Should we be concerned? Despite the Harlequin being a quite handsome bug, there are fears its explosive spread could result in threats for other ladybird species, either directly or indirectly. They are reportedly very aggressive toward other ladybirds and even humans! Although I must say I have often collected them by hand and they seem not to be aggressive when being handled carefully, in the same way the 7-spot. They eat larvae and eggs of ladybirds if aphids become scarce. Their populations might not be kept in check by predators and parasites. Also, they hibernate in houses in a communal way and they can become a nuisance.

 In Hull, the Harlequin became very common in 2007, but didn't see many in summer 2008, maybe the gloomy, wet summer didn't suit them!