When are ticks active and at what temperature? - briefly
Ticks become active when temperatures stay above approximately 7 °C (45 °F) with moderate to high humidity, typically from early spring through late autumn. Peak activity is observed between 15 °C and 30 °C (60 °F–86 °F).
When are ticks active and at what temperature? - in detail
Ticks become questing insects when ambient conditions allow them to locate hosts. Activity generally starts when temperatures rise above the lower thermal limit of about 4 °C (40 °F). Below this threshold metabolic processes slow, and ticks enter a dormant state. Once the temperature reaches 10 °C (50 °F), most species begin regular host‑seeking behavior, and the number of active individuals increases sharply as the day warms.
The peak of questing occurs between 15 °C and 30 °C (59 °F–86 °F). Within this band, ticks move frequently, climb vegetation, and wait for passing mammals or birds. Relative humidity must remain high, typically above 70 %, to prevent desiccation. When temperatures exceed roughly 30 °C (86 °F) and humidity drops, activity declines because water loss accelerates. Some species, such as the Lone Star tick (Amblyomma americanum), can remain active up to 35 °C (95 °F) if humidity stays above 80 %.
Seasonal patterns reflect these thermal limits:
- Early spring (March–May in temperate zones): temperatures climb past 10 °C, initiating the first wave of activity.
- Summer (June–August): temperatures often sit in the optimal 20–30 °C range, producing the highest tick densities.
- Early autumn (September–October): cooling temperatures keep activity above 10 °C, extending host‑seeking until frost.
- Winter (November–February): temperatures fall below 4 °C, and ticks enter diapause, remaining hidden in leaf litter or soil.
Geographic variation shifts the calendar. In southern regions where winter temperatures stay above 5 °C, ticks may be active year‑round, with a brief reduction during the hottest, driest months. In northern latitudes, activity may be confined to a three‑month window from late May to early August.
Life‑stage differences also affect temperature sensitivity. Larvae and nymphs, being smaller, require higher humidity and are more restricted to the lower end of the optimal temperature range (10–20 °C). Adults tolerate a broader span, remaining active up to 30 °C provided moisture is sufficient.
Key temperature thresholds for common species:
- Blacklegged tick (Ixodes scapularis): activity begins at 4–7 °C; optimal 13–25 °C; declines above 30 °C.
- American dog tick (Dermacentor variabilis): active from 5 °C; peak 15–28 °C; reduced when >32 °C.
- Lone Star tick (Amblyomma americanum): starts at 6 °C; optimum 18–30 °C; can persist to 35 °C with high humidity.
In summary, tick questing is driven by a temperature window of roughly 4 °C to 30 °C, moderated by humidity, with species‑specific nuances and seasonal shifts that reflect local climate patterns.