Wasp Spider boom at Thames Road Wetland

There is an unusually large number of Wasp Spiders (Argiope bruennichi) at Thames Road Wetland this year, something first noticed by Jason Steel a week ago when he counted 32. Yesterday I managed 38, though I wouldn’t say this was the result of a thorough search, just an attempt to beat Jason’s figure. The species was first found at the site a few years ago but has not been spotted again for some time.

The animals are inhabiting a general area of approximately 964 square metres, giving an average of 1 per 25.4 sq m. However, the actual density in the most suitable parts of the habitat is much higher, with it being possible to find several quite close together. All the webs, which have a distinctive zig-zag weave below the centre, are amongst longish fine grasses, and appear not to be in areas dominated by dead herbaceous  material. This may be because the spiders are seeking prey such as Grasshoppers, one of which was seen to be rapidly pounced upon and wrapped in silk when it made the mistake of  jumping into a web.

Wasp Spider at Thames Road Wetland (Photo: Chris Rose)

Wasp Spider at Thames Road Wetland.  The zig-zag weave below the centre, called the stabilimentum, can be clearly seen. Its function is not understood. (Photo: Chris Rose)

The zigzagweave below the centre of the web, called the stabilimentum, is distinctive, but its function is not understood. (Photo: Chris Rose)

The same Wasp Spider from a slightly different angle. (Photo: Chris Rose)

The Wasp Spider was first recorded in the UK in the 1920s, but has become more prominent in recent years, and has been recorded from various parts of Bexley including Erith Marshes (Crossness), Grasmere allotment site  and Streamway.

It would be interesting to hear whether this apparently exceptional number of individuals is a freak event or is matched by increased numbers elsewhere in the Borough.

Chris Rose, Volunteer Site Manager, Thames Road Wetland

 

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