When do ticks go dormant in autumn? - briefly
Ticks enter diapause when autumn temperatures fall below about 10 °C and day length shortens, usually in late September to early October. Activity remains minimal until spring warming resumes.
When do ticks go dormant in autumn? - in detail
Ticks reduce activity as temperatures drop and daylight shortens in the fall. Most species enter a state of diapause when daily maximum temperatures fall below approximately 10 °C (50 °F) and night‑time temperatures approach 0 °C (32 °F). The decline in photoperiod, usually below 12 hours of light, reinforces this physiological shift.
During this period, adult and nymphal stages cease questing, seeking hosts less frequently, and often retreat to leaf litter or soil crevices where microclimate remains relatively stable. Larvae may continue limited activity if sheltered in humid microhabitats, but overall host‑seeking behavior diminishes sharply.
Key factors influencing the onset of dormancy:
- Temperature: Sustained daytime highs under 10 °C trigger metabolic slowdown.
- Photoperiod: Day lengths shorter than 12 hours accelerate diapause hormone production.
- Relative humidity: Values above 70 % allow ticks to survive in the leaf litter while inactive; lower humidity can force earlier mortality.
- Geographic latitude: In northern regions, the transition occurs in early September; in temperate zones, it typically begins in late September to early October; in subtropical areas, activity may persist until November.
Species‑specific notes:
- Ixodes scapularis (black‑legged tick) generally ceases questing when temperatures drop below 7 °C, with diapause beginning in mid‑September in the northeastern United States.
- Dermacentor variabilis (American dog tick) reduces activity earlier, often by early September, due to its higher temperature tolerance.
- Rhipicephalus sanguineus (brown dog tick) can remain active longer in indoor environments, but outdoor populations enter dormancy when ambient temperatures fall beneath 12 °C.
The dormant phase lasts until winter temperatures rise above the activity threshold, typically in late March to early May, depending on regional climate. During this interval, ticks rely on stored reserves and reduced metabolic rates to survive.