Southern Marsh Orchids

Southern Marsh Orchids

Saturday 25 January 2014

Spiders again

I was in the grounds of Llandaff cathedral this morning, and as the temperature was relatively warm for the time of year, I thought I would have a look for spiders.  Primarily I wanted to have a look for Segestria florentina, a species which favours port towns and is increasing its range, but has not yet been seen as far west as Cardiff .  I didn't find Segestria unfortunately, but there were several of this species, Amaurobius similis, both adult males and females.
Amaurobius similis
Both A similis and S florentina often make their homes in holes in crumbling mortar making churches and churchyard walls a good place to look for them.  Their retreats are silk-lined tubes and in the case of A similis have a scruffy layer of cribellate silk radiating out from them in the immediate vicinity of the entrance.  This silk often contains the remains of previous meals which can give an idea of what they are feeding on.  The silk is used by the spider to warn them of an approaching meal as the strands are pulled and plucked by unwary insects.  Because they inhabit silk-lined tubes, some creativity is needed to lure them out into the daylight to find out which species you have.  A tuning fork is very effective in simulating the vibrations of an insect, as is an electric toothbrush apparently though I have not tried the latter.  The tuning fork elicits a lightning-fast and aggressive feeding response from the spider so it's probably good advice to keep fingers out of the way! 

There was a TV crew filming in the Cathedral this morning and I can tell you with some certainty that  kneeling next to a wall holding a tuning fork gets some very curious looks!

 A similis is a very common species, as can be seen from the Spider Recording Scheme map below.  Although there are few records from Glamorgan, I would be very surprised if this species is not quite common and widely distributed here too.

Source: Spider Recording Scheme/British Arachnological Society (2012) Website and on-line database facility

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