When are fleas active? - briefly
Fleas reach peak activity in warm, humid conditions—generally 70‑85 °F (21‑29 °C) during spring and summer—and may persist year‑round indoors where temperature and moisture remain suitable. Their activity declines sharply when temperatures drop below 50 °F (10 °C) and humidity falls.
When are fleas active? - in detail
Fleas are most active when temperature and humidity create favorable conditions for development and host seeking. Their activity peaks between 70 °F and 85 °F (21 °C–29 °C) with relative humidity above 50 %. Below 50 °F (10 °C) metabolic rates drop sharply, and the insects enter a dormant state, reducing feeding and movement.
During warm months, adult fleas emerge from the pupal cocoon, seek blood meals, and reproduce rapidly. A single female can lay up to 50 eggs per day, leading to exponential population growth if environmental parameters remain optimal.
In cooler periods, adult fleas may remain in the environment but refrain from feeding. Eggs, larvae, and pupae survive longer at lower temperatures, awaiting a rise in warmth to resume development.
Key factors influencing activity cycles:
- Temperature: 70–85 °F stimulates biting and egg production; <50 °F suppresses it.
- Humidity: >50 % prevents desiccation of eggs and larvae; low humidity accelerates mortality.
- Host availability: Presence of mammals or birds provides blood meals, prompting movement.
- Seasonal patterns: Spring and early summer often see the highest infestation levels; late fall may see a decline, though indoor environments can sustain activity year‑round if heating maintains suitable temperatures.
Indoor heating can extend the active period, allowing fleas to thrive throughout winter in homes, shelters, and kennels. Regular temperature control, humidity management, and prompt removal of infested animals interrupt the cycle and reduce overall activity.