Species profile

Castor bean tick

Ixodes ricinus

Ixodes ricinus is a widespread European hard tick that feeds on many mammals, birds and reptiles, including humans. It is the tick species of greatest concern for human health in the United Kingdom and the principal UK vector of Lyme borreliosis.

Adult female Ixodes ricinus tick on the left and smaller adult male on the right
female_and_male · Adult · unfed

Image credit:Alan R Walker • Licensed under CC BY-SA 3.0 • Source: Wikimedia Commons Licence terms — Abrirá numa nova janela.Source — Abrirá numa nova janela.

Engorged adult female Ixodes ricinus castor bean tick after a blood meal
female · Adult · engorged

Image credit:MicrocosmicWorld / Wikimedia Commons Licence terms — Abrirá numa nova janela.Changes: Resized proportionally from 7166 × 4778 px to 5338 × 3559 px for Shopify compatibility; no crop or content alteration.Source — Abrirá numa nova janela.

Also known as: Sheep tick, Deer tick

Image gallery

Quick facts

Family: Ixodidae. Genus: Ixodes. Hard tick. Recorded life stages: egg, larva, nymph and adult.

Identification

Larvae have six legs; nymphs and adults have eight. Adult females have a dorsal scutum covering only the anterior body, while the adult male scutum covers almost the entire dorsal surface. Microscopic characters may be required.

Ixodes genus characters and species-level morphology may require microscopic examination. Engorgement can obscure useful characters.

May be confused with Ixodes hexagonus and Ixodes persulcatus. Host, colour or photograph alone is not sufficient for reliable confirmation.

A photograph alone cannot always confirm Ixodes ricinus. Where species confirmation matters, use an authoritative key and appropriate expert examination.

Sex and appearance differences

Adult females have a scutum covering only the anterior dorsal surface, allowing substantial expansion during feeding. Adult males are smaller and the scutum covers almost the whole dorsal surface. Larvae have three pairs of legs; nymphs and adults have four pairs.

Life cycle

A three-host life cycle is typical. Larvae, nymphs and adult females require a blood meal, and each parasitic stage normally feeds on a separate host. Duration is often approximately three years but varies with climate and host availability.

Life stages

  • Egg
  • Larva
  • Nymph
  • Adult

Seasonal activity

Potentially active throughout the year. UK nymph activity is greatest in spring and commonly peaks between April and June. Phenology varies geographically and between years and may include spring and autumn peaks.

Hosts

  • Humans (Homo sapiens)
  • Deer
  • Cattle (Bos taurus)
  • Small mammals
  • Birds
  • Reptiles

Habitats

  • Woodland
  • Grassland and rough pasture
  • Parks and wildlife-accessible gardens

Distribution

Established and widespread in the United Kingdom. Presence records, establishment, habitat suitability and disease risk must be interpreted separately.

Presence, established populations, habitat suitability and disease risk are distinct evidence categories.

Countries and regions

  • United Kingdom — present

    Included in the UKHSA tick species profiles for the United Kingdom.

  • Europe — present

    ECDC publishes confirmed European distribution data for this species.

  • England — present

    UKHSA surveillance maps and records identify Ixodes ricinus across England.

  • Scotland — present

    UKHSA surveillance maps and records identify Ixodes ricinus across Scotland.

  • Wales — present

    UKHSA surveillance maps and records identify Ixodes ricinus across Wales.

  • Northern Ireland — present

    UK-wide surveillance describes Ixodes ricinus as widespread across the UK, while official Northern Ireland guidance confirms exposure to Lyme-carrying ticks within the UK and Ireland.

Medical and veterinary relevance

Frequently bites humans. It is the principal UK vector of Lyme borreliosis. Pathogen detection, vector competence and local disease risk are distinct evidence categories.

Feeds on livestock, companion animals and wildlife and is associated with pathogens of veterinary importance.

Pathogens and diseases

  • Lyme borreliosis — disease

    Ixodes ricinus is the principal UK vector of Borrelia burgdorferi sensu lato. Vector status and individual infection risk are separate questions.

  • Tick-borne encephalitis — disease

    Ixodes ricinus is a recognised vector of tick-borne encephalitis virus in relevant endemic settings; presence of the tick does not itself establish local disease risk.

  • Anaplasmosis and tick-borne fever — disease

    Association and vector relevance depend on pathogen strain, host and geography.

  • Babesiosis — disease

    Species, host and geographic context are required when describing Babesia associations.

  • Louping ill — disease

    A veterinary and wildlife disease association reported for Ixodes ricinus.

  • Rickettsia helvetica (Rickettsia helvetica) — pathogen

    Detection and transmission evidence must not be presented as proof of local clinical disease risk.

Detection of a pathogen in a tick does not by itself establish that the species is a confirmed vector.

Vector and pathogen evidence

Confirmed principal UK vector of Borrelia burgdorferi sensu lato. It is also a recognised vector or reported vector-associated species for other pathogens, but each association must retain its source-specific evidence category. Detection alone does not prove vector competence or local transmission.

Medical importance

Frequently bites humans. Small nymphs are important in exposure because they may be overlooked. This profile describes evidence and does not diagnose infection or predict an individual’s risk.

Veterinary importance

Feeds on livestock, companion animals and wildlife and has substantial veterinary relevance. Pathogen, host and geographic context must be stated for individual disease claims.

Prevention and removal guidance

Use appropriate clothing and repellents where suitable, remain on clear paths where practical, and check people, clothing and animals after exposure to tick habitat. Follow current public-health and veterinary guidance.

Remove an attached tick promptly with fine-tipped tweezers or a purpose-designed tick-removal tool. Grasp close to the skin and pull upward slowly and firmly without crushing the tick. Seek appropriate professional advice if concerning symptoms develop.

Important identification and health information

Educational information and limitations

Photographs and visible features may be insufficient for definitive identification.

This educational information is not a diagnosis or a substitute for medical or veterinary advice.

This educational information does not replace examination or advice from a qualified veterinary professional.

Presence, established populations, habitat suitability and disease risk are distinct evidence categories.