When does flea activity begin?

When does flea activity begin? - briefly

Flea activity generally starts in early spring, once temperatures consistently reach about 55 °F (13 °C) and humidity rises. In milder regions the onset can occur earlier, extending the active period into late winter.

When does flea activity begin? - in detail

Fleas become active when environmental conditions support their development cycle. Temperatures consistently above 10 °C (50 °F) accelerate egg hatching, larval growth, and adult emergence. Relative humidity near 70 % further enhances survival rates.

In temperate regions, the onset typically occurs in early spring. Soil and indoor temperatures reach the necessary threshold in March‑April, allowing the first generation to appear. In warmer climates, activity may commence as early as February and persist year‑round.

Key variables that determine the start of flea activity:

  • Ambient temperature sustained above 10 °C
  • Relative humidity around 70 %
  • Availability of hosts for blood meals
  • Day length influencing microclimate warmth

Geographic variations shift the calendar. Northern latitudes experience delayed activation, often not until late April. Southern latitudes report earlier emergence, sometimes in February. Altitude also delays activity; higher elevations require additional warming periods.

Effective monitoring includes regular inspection of pet bedding, use of flea traps, and temperature logging in areas where pets rest. Early intervention, such as applying preventive treatments before the first adult fleas are detected, reduces infestation risk.