When does tick activity decline? - briefly
Tick activity falls sharply as temperatures dip below 15 °C and daylight hours shorten, usually in late summer to early autumn. This decline follows the midsummer peak when environmental conditions become less favorable for host‑seeking behavior.
When does tick activity decline? - in detail
Tick activity reaches its peak in spring and early summer when temperatures rise above 7 °C and relative humidity remains above 80 %. As environmental conditions shift, several factors trigger a measurable decrease in questing behavior.
Temperatures exceeding 30 °C suppress activity because desiccation risk rises sharply. At this threshold, ticks retreat to the leaf litter or soil to conserve moisture, and host‑seeking movements decline sharply. The same effect occurs when relative humidity falls below 70 %, regardless of temperature, leading to reduced surface activity.
Photoperiod also influences the seasonal pattern. Shortening daylight hours in late summer signal the approach of unfavorable conditions, prompting physiological changes that limit questing. In many temperate regions, the decline begins in August and intensifies in September, coinciding with day lengths under 12 hours.
Host availability contributes to the downward trend. As mammals such as deer and rodents reduce movement during cooler months, the stimulus for ticks to seek blood meals diminishes, reinforcing the seasonal dip.
Key environmental thresholds that mark the onset of reduced activity:
- Air temperature: >30 °C (dry heat) or <7 °C (cold)
- Relative humidity: <70 %
- Day length: <12 hours
- Soil moisture: depletion of the upper 5 cm layer
Regional variations modify these values; for example, in Mediterranean climates the decline may start later (mid‑September) because summer humidity remains higher, whereas in northern latitudes the reduction can begin as early as late July.
Overall, the decrease in tick questing is a predictable response to combined thermal stress, moisture loss, shorter photoperiod, and diminishing host presence, typically occurring from late summer through early autumn.