Spiders

For a number of years I was my work’s Local Environment Co-ordinator which is primarily concerned with monitoring the environment inside and outside of the premises and making sure that we could do all humanly practicable to safeguard wildlife and encourage more. It all helped with our IPM (Integrated Pest management). Two of the most important predators to be found inside a glass house is the spider and mite of which we have some unusual ones in ours.

The above photo is of Uloborus plumipes. Looks big doesn’t it? The females are only about 6 mm long and this one was photographer down a powerful binocular microscope whilst held in a petri dish. It is not native to Britain but turned up simultaneously in the heated parts of garden centres and nurseries during the same week in the early 1990s in Reading, Liverpool and Southampton and must have been introduced through one of the ports on a consignment of plants from abroad. Since then it has spread rapidly and occurs as far north as Ambleside, Cumbria. It is found all over European in commercial greenhouses and also in Africa and Asia. It is sometimes brought into houses on houseplants and is also known as the 'Feather-legged lace weaver'. Young spiders often camouflage themselves in a line of dead insect bodies across the centre of the web, on first inspection it is difficult to tell that this is a spider at all. Sometimes this spider makes stabilimentum in its web.

This spider, like others in the genus Uloborus, lack venom glands and so they have to employ different means to kill their prey. When something lands in the web the Uloborus locates the the object by plucking different strands. When it has located the prey it moves in the direction of where it thinks the prey is and shakes itself in the web. When the spider is sure of the prey's location it will immediately wrap it up tightly in allot of silk. When this is done the spider will cut the newly wrapped prey free and take it to the centre of the web. The spider will hold the bundle in its second and third pairs of legs and revolve it whilst drawing threads from her spinnerets with the fourth pair. Only after this second wrapping is complete does the spider bite the prey, since the spider lacks venom glands the prey is very often eaten alive.

They have a very distinctive egg sac that can often be seen empty attached to house plants. It is flat, papery and brown in colour and about 0.5 cm long. The tiny miniature spiders can sometimes be found around the sack. The colour of the spiders vary much from a pale cream to almost black.

I can tell at which point the spider first came into our nursery as the area is now festooned with old webs. They appear to spin their webs and then, when the web becomes too damaged, move on to a new site without recycling their web. This causes a very unsightly mass of old dusty webs which are hard to clean up! They are now found all over the nursery.

and Pip Taylor.

Another spider that is found on or nursery which is also not native to Britain is the American house spider Achaearanea tepidariorum. They make their tangled webs low down near the floor and under the benches on the nursery. They don’t seem to do much but sit upside down waiting for their pray. They are often found sitting next to their egg sack which is round with a pointed end. They appear to be fearless and very able to catch and kill all manner of things including the much larger British house spider Tegeneria domestica. I’ve watched this done and the venom produced will kill one of these spiders in seconds. The venom is injected at a leg joint. Other pray include ground beetles (see below) and centipedes.

Below is a photo of Larinioides sclopetarius. On seeing this spider for the first time I thought it a variation of Araneus diadematus (Garden Spider). One end of a glass house, which is the south side, is festooned with the webs of this spider. Individuals of all sex and sizes have jammed every available space with their webs which must create a formidable barrier to any flying insect which finds itself inside the glass house. This spider is found almost exclusively on man made objects, preferably metal ones, and very rarely on vegetation.

Many thanks to Peter R. Harvey of the British Arachnological Society.

Without his help I would have struggled and then got my identifications wrong!

All photos Copyright of Russ Woodcock and myself.

There is another spider I’d like to introduce and that’s the Walnut Orb Web (Nuctenea umbratica) which was first recorded in Britain in 1978. Apparently umbratica means shy and slow (or something like that) and they generally are but I have seen them rush out from their cover, when I pass, and wave their front legs at me as though to say “Got you!”. Then they seem to realise that I’m a bit big to handle and run for cover!

The photo below is a very gratifying one of an American house spider being devoured! I thought Achaearanea was top dog in the glass house but evidently not.

There are many types of “Money Spider” and it is hard to believe that such tiny individuals are no different from their larger cousins till they are viewed under a high powered binocular microscope. Below are three photos of a female and two males. These individuals are very common where I work and believe it or not are only a couple of millimetres long.

Below is another orb web spider common to the British Isles Tetragnatha montana. It isn’t very large and is hard to spot as it tends to sit with its legs held out “fore and aft” giving it the appearance of a stick. They do have large mouth parts which, unfortunately, can’t be see too well in this photo.

Here’s some photos of an interesting spider. This one cropped up in one of our glass houses in Welford on Avon and started to breed. A substantial colony thrived for a year but eventually succumbed to the cold of winter. It is not dissimilar to out “Daddy Longlegs” spider (Pholcus phalangoides) in our homes but is rather more colourful. It is called Holocnemus pluchei and found mainly in the USA. Our colony was the first ever recorded in Britain and was mentioned in the Spider Recording News February 2007.