When is an encephalitic tick active? - briefly
These ticks are most active from early spring through early summer, generally March – June, when temperatures exceed about 7 °C (45 °F). Their activity drops sharply after midsummer as humidity declines and temperatures rise above 30 °C (86 °F).
When is an encephalitic tick active? - in detail
Encephalitic ticks, primarily Ixodes ricinus in Europe and Ixodes scapularis in North America, become active when environmental conditions support questing behavior. Activity peaks during spring and early summer, coinciding with rising temperatures above 7 °C (45 °F) and increasing daylight. A secondary rise occurs in autumn as temperatures decline to 5–10 °C (41–50 °F) and humidity remains above 70 %.
- Spring (March–May): Nymphs emerge, seeking hosts; peak questing at 10–15 °C (50–59 °F).
- Early summer (June–July): Adult females search for blood meals; activity sustained up to 25 °C (77 °F) but diminishes above 30 °C (86 °F).
- Autumn (September–October): Adults and late‑stage nymphs resume activity; optimal conditions 8–14 °C (46–57 °F) with high leaf litter moisture.
- Winter: Activity virtually absent; ticks remain in diapause within leaf litter and soil.
Geographic factors modify these patterns. In temperate zones with milder winters, activity may start earlier (late February) and extend into November. In mountainous or northern regions, the active season shortens to May–September due to lower temperatures and shorter daylight periods.
Microclimate influences questing height. Ticks ascend vegetation when humidity exceeds 80 % and retreat to the forest floor during dry periods. Daytime activity is common; however, some populations exhibit increased questing at dawn and dusk when temperature and humidity are most stable.
Understanding these temporal dynamics assists in risk assessment and preventive measures, such as timing of personal protective equipment and targeted acaricide applications.