Blood-filled tick, coloured scanning electron micrograph (SEM). The tick is swollen in size after feeding on the blood of its mammal host. The legs are protruding from its body either side of its mouthparts (centre) This is a common sheep tick (Ixodes ricinus), the principal vector of Lyme disease in Europe. It is common in the damp underbrush of European woods and attacks various domestic and wild animals, including dogs and humans. It carries the bacterium (Borrelia burgdorferi) that causes Lyme disease. Magnification: x18 when printed 10cm wide.