Mapping ticks (Acari: Argasidae, Ixodidae) and informing local public action: Insights from the United Kingdom Tick Surveillance Scheme (2021-2024)

• The Tick Surveillance Scheme is a long-running UK citizen science initiative. • Ixodes ricinus is the main vector detected across the UK. • Tick distribution maps for several species have been updated and presented. • Non-native species that present novel health threats continue to be detected. • A new tick-bite indicator was developed to guide public health actions. The Tick Surveillance Scheme (TSS) is a citizen science initiative which relies on public and professional submissions to monitor tick species distribution, seasonal exposure, and host associations across the United Kingdom (UK). During the period 2021–2024, 3182 tick records were received and 27 tick species were detected. The data confirm that Ixodes ricinus , the primary vector for Lyme disease and Tick-borne encephalitis, remains the most common tick in the UK. The TSS continues to detect imported tick species, underscoring the risk of novel pathogens entering the country, with new species like Hyalomma excavatum and Rhipicephalus pulchellus reported for the first time. The scheme also provides crucial evidence of non-endemic species like Hyalomma marginatum being found on hosts without history of foreign travel, although establishment risk is currently considered low. In addition to updated species distribution maps, a new tick-bite incidence metric has been developed and translated into a heat map for England and Wales. Updated regularly, this enables targeted public health interventions and awareness campaigns at the local authority level, providing a proxy for potential tick exposure. Tick submissions are likely underrepresented from Scotland and Northern Ireland, suggesting a need to strengthen outreach in these areas to improve data accuracy.