Why are there few ticks in summer? - briefly
Ticks are less abundant in summer because high temperatures and low humidity cause rapid desiccation, limiting their activity and survival. Many species also complete their life cycle before the hottest period, leaving fewer individuals active during that season.
Why are there few ticks in summer? - in detail
Ticks are ectoparasites whose activity depends on external temperature, relative humidity, and host presence. During the hottest months, ambient temperatures often exceed the optimal range for questing behavior (typically 10‑25 °C). When temperatures rise above 30 °C, ticks reduce movement to avoid lethal dehydration, resulting in fewer encounters with hosts.
Relative humidity declines in summer, especially in open habitats. Ticks lose water rapidly through their cuticle; low moisture levels trigger a physiological response that forces them to retreat into the leaf litter or soil, where they remain inactive until conditions improve. This moisture limitation directly suppresses the proportion of the population that seeks hosts.
Host availability also shifts seasonally. Many mammals and birds that serve as primary blood meals either migrate, reduce activity, or occupy cooler microhabitats during peak heat. Consequently, the probability of a tick locating a suitable host diminishes, reinforcing the drop in observed tick numbers.
Additional factors influencing the summer decline include:
- Photoperiod: Longer daylight hours increase exposure to solar radiation, accelerating desiccation risk.
- Predation and pathogen pressure: Elevated temperatures favor predators (e.g., ants, beetles) and microbial agents that reduce tick survival.
- Developmental cycle timing: Some species complete larval and nymphal stages in spring, emerging as adults in late summer, but adult activity peaks in cooler autumn months rather than the hottest period.
Collectively, thermal stress, reduced humidity, altered host behavior, and increased mortality pressures create a seasonal trough in tick activity during the warmest part of the year.