Ixodes ricinus is a geographically widespread species and is Europe’s commonest tick. It has been collected throughout the British Isles. Like all other ticks, Ixodes ricinus is a blood-feeding ectoparasite of vertebrates. Its hosts are mainly small to large mammals, but birds and sometimes reptiles are also parasitized. Egg-laying and moulting occur away from the host, ideally in thick vegetation that maintains a humid atmosphere within it. Infestations can cause a decline in host health due to blood loss. Also tick paralysis, thought to be a result of a neurotoxin introduced during feeding, may occur. However, Ixodes ricinus is most well-known as a vector of diseases, particularly Lyme borreliosis (Lyme disease).