When do ticks increase in number?

When do ticks increase in number? - briefly

Tick numbers peak in late spring to early summer, when warm temperatures and high humidity accelerate their life cycle. Milder winters also lead to larger populations the following season.

When do ticks increase in number? - in detail

Ticks reach peak abundance during late spring and early summer. Rising temperatures above 7 °C (45 °F) trigger the start of questing activity, while humidity levels above 80 % prevent desiccation and enable sustained movement. The combination of warm, moist conditions creates an optimal environment for all active stages—larvae, nymphs, and adults.

Key factors influencing population surges:

  • Temperature: Development rates accelerate as ambient heat rises; each 10 °C increase shortens the molt period by roughly 20‑30 %. Warmer seasons therefore compress life‑cycle timelines, allowing multiple generations within a single year in some regions.
  • Relative humidity: Moisture retention is critical for cuticular water balance. When humidity drops below 60 %, questing ticks withdraw to the leaf litter, reducing visible numbers.
  • Host availability: Peaks in small‑mammal activity, especially rodents, provide abundant blood meals for larvae and nymphs. Deer abundance correlates with adult tick density, as females require large hosts for egg production.
  • Photoperiod: Longer daylight hours stimulate diapause termination, aligning emergence with favorable climatic windows.
  • Geographic latitude: In temperate zones, the main increase occurs from May to July; in subtropical areas, activity may extend from February through October, with a secondary rise in autumn.

Long‑term trends show that milder winters and earlier springs, driven by climate change, shift the onset of tick activity forward by several weeks. This results in extended transmission seasons for tick‑borne pathogens and higher overall population levels.

In summary, tick numbers rise when temperature, humidity, and host presence converge to support active questing and rapid development, typically during the warm, moist months of the year, with regional variations dictated by latitude and local climate patterns.