Why are there no ticks in the south? - briefly
The southern climate’s high temperatures and low humidity disrupt the developmental stages of «ticks» and limit host availability. Sparse vegetation and dry soil further eliminate the microhabitats required for their survival.
Why are there no ticks in the south? - in detail
The lack of tick populations in many southern regions results from a combination of climatic, ecological, and biological factors.
Temperatures that regularly exceed the optimal range for tick development accelerate desiccation and reduce survival rates. Heat‑induced dehydration limits the ability of larvae, nymphs, and adults to maintain moisture balance, especially in open habitats where shade is scarce.
Humidity levels in arid or semi‑arid southern zones often fall below the threshold required for successful molting. Low relative humidity shortens questing periods, decreasing the chance of locating hosts.
Host availability influences tick distribution. Certain vertebrate species that serve as primary reservoirs are either absent or present at low densities in these areas. The scarcity of suitable mammals and birds diminishes the opportunities for blood meals, interrupting the tick life cycle.
Vegetation structure affects microclimate conditions. Sparse ground cover reduces leaf litter and leaf‑litter moisture, eliminating the sheltered environments ticks need for development and overwintering.
Species‑specific limits also play a role. The most common disease‑vector ticks, such as Ixodes scapularis and Dermacentor variabilis, have physiological tolerances that exclude them from regions where summer temperatures regularly surpass 35 °C or where winter lows are insufficient for diapause induction.
Human interventions contribute to the observed pattern. Extensive land‑use changes, including agriculture and urbanization, create inhospitable terrain for ticks and disrupt wildlife corridors that would otherwise support their spread.
In summary, the combination of extreme heat, low humidity, limited host populations, unsuitable vegetation, species‑specific thermal thresholds, and anthropogenic landscape alteration collectively prevents tick establishment in many southern locales.