When do ticks retreat into the ground? - briefly
Ticks typically descend into leaf litter or the upper soil layer during late summer and early autumn, especially after engorgement, to find the humidity needed for molting or overwintering. This downward movement occurs when the questing period ends and environmental conditions become less favorable above ground.
When do ticks retreat into the ground? - in detail
Ticks seek refuge in the soil primarily as temperatures fall below the activity threshold for their stage. For most temperate species, this occurs when daily maximum temperatures drop to approximately 10 – 12 °C and night‐time lows approach 5 °C. The decline in daylight hours reinforces the descent, with photoperiods shorter than 12 hours prompting many nymphs and adults to move downward.
Seasonal timing varies by region but follows a consistent pattern:
- Early autumn – larvae and unfed nymphs begin to burrow after the first sustained cool spell.
- Mid‑to‑late autumn – engorged adults, having completed a blood meal, retreat to lay eggs in protected leaf litter or soil.
- Winter – all stages remain underground in a state of diapause, resuming activity only when temperatures rise above the threshold.
Humidity plays a secondary role. Relative humidity above 70 % reduces desiccation risk, allowing ticks to remain near the surface longer. When humidity declines, ticks are more likely to seek deeper, moister layers of soil.
Species‑specific behavior influences timing. Ixodes ricinus typically descends in September in northern Europe, whereas Dermacentor variabilis may wait until October in the United States. Some tropical ticks, such as Amblyomma cajennense, exhibit less pronounced seasonal retreat, moving underground only during extended dry periods.
Understanding these patterns assists in predicting periods of reduced human exposure and informs timing for acaricide applications or habitat management aimed at lowering tick populations.