Wiltshire and Swindon Biological Records Centre

Raft Spider - Dolomedes fimbriatus

Landford Bog, the Wiltshire Wildlife Trust Reserve, on the edge of the New Forest is a good place to see the Raft Spider. The best time to see it is May to August.

Raft Spider, WSBRC/John Notman


 

Habitat

The Raft Spider is fairly common in boggy habitats such as swamps where there is permanent open water.

Description

Striking pale yellow stripes along either side of its body make the Raft Spider an easily identifiable spider; these stripes tend to be brighter on males. The rest of their body and their legs are dark brown in colour; it has long sturdy legs and an oval shaped abdomen. The Raft Spider is one of our largest spiders, the females are typically larger than the males - females are approx 22mm and males approx 13mm.

Biology

It is also known as the fishing spider in Europe as it hunts from vegetation next to areas of water. It rests its first two legs on the water through which it senses its prey mainly tadpoles and insects, and then pulls it out of the water. Because of its large size it is also capable of taking prey such as damselflies and small fish! It will attract fish by gently vibrating the surface of the water. It will also hunt on the edges of these small pools of water amongst the damp vegetation. If it feels threatened it will hide underwater holding onto waterside vegetation, it can stay there for up to an hour.

Females tend to be very aggressive towards the males, especially during courtship and like many other species of spider may actually eat the male! After mating the female carries the eggs underneath her body in sacs until it’s time for the spiderlings to emerge, she will then leave the sac on a leaf and spin a protective layer around it. She will stay with this until the spiderlings emerge.