Fen raft spider continues to thrive in Norfolk and Waveney

The fen raft spider was brought back from the brink of extinction thanks to a successful breeding programme and there are now thousands across the region. 

Before 2010 the spider was incredibly rare but is now thriving at sites such as the Mid Yare National Nature Reserve in Norfolk and at Castle Marshes and Carlton & Oulton Marshes near Lowestoft thanks to the programme pioneered by Dr Helen Smith.

The spiders skate across the water (Image: Ron McIntyre) A striking ambush predator with a dark body and cream stripes down the side, it can have a leg span of up to 8cm and a body the size of a small mouse. 

Ben Lewis, an RSPB warden at Sutton Fen, said the spiders flourish due to the sites providing a perfect habitat of grazed grassland and good-quality ditches.

Last year, a census at Strumpshaw Fen counted 3,750 spiders at the reserve. 
Fen raft spiders are the UK's largest spider (Image: Ron McIntyre) As their name suggests, the spiders raft across the water without breaking the surface tension eating a variety of prey such as dragonflies, other spiders, tadpoles, pondskaters and even small fish.

But Mr Lewis says the scariest thing about the spiders is probably their size.

"I've never heard of anyone being bitten by one," he said.  "They won't have people fleeing from their bedrooms.

Early September is a good time to spot them at Strumpshaw Fen (Image: James Lowen) "They would only be in that good quality land and I would be extremely surprised if anyone even found one in their garden or pond."

For anyone who would like to see one, he suggests going along to Strumpshaw Fen and having a look in the ditches. 

The females have two broods with the second usually coming out early to mid-September. 

The webs can be up to 25cm across - the size of a regular pizza - and the egg sacs are the size of a marble.