Phenology of questing Ixodes frontalis nymphs reveals a late-winter to early-spring activity peak.

Although Ixodes frontalis is widespread across Europe, including urban and peri‑urban habitats, several aspects of its biology remain undescribed. One such aspect is the population dynamics of its nymphal stage, which has so far been reported from limited sample sizes, preventing the identification of its peak abundance. To fill this knowledge gap, we conducted a year-long monthly survey at four locations in France representing three different climates. The sampling protocol - based on the flagging method performed under bamboo bushes - was designed to maximize the likelihood of capturing the nymphal stage. Based on the 400 nymphs collected during this survey, a clear peak of I. frontalis nymphs was observed around March (February to April) across all four sites, with an additional peak in August at one site. The population dynamics of the larval stage - based on semi-quantitative counts - showed the same previously described pattern, with a peak in late autumn. Twenty adults (11 females and 9 males) were also collected from March to December, but these data did not allow a clear identification of a peak abundance. Because several bird species - such as blackbirds, song thrushes, European robins, and Eurasian blackcaps - serve as feeding hosts for both I. ricinus and I. frontalis, and are also reservoirs for pathogens transmitted by these ticks, the implications of our findings for the eco-epidemiology of tick-borne diseases are discussed.