When do fleas go into dormancy? - briefly
Adult fleas enter a dormant diapause when daylight shortens and temperatures fall, typically in late autumn. They remain inactive until warmer, longer‑day conditions return in spring.
When do fleas go into dormancy? - in detail
Fleas enter a dormant phase primarily during the adult stage when environmental conditions become unfavorable for reproduction and host activity. The transition to inactivity is triggered by a combination of low ambient temperature, reduced daylight length, and limited host availability. Laboratory studies show that temperatures below 10 °C (50 °F) and photoperiods shorter than 12 hours per day markedly increase the proportion of adults that cease feeding and remain in a non‑reproductive state. In natural settings, this response aligns with the onset of winter in temperate zones, when mammals and birds reduce movement and shelter in insulated areas.
Key environmental parameters influencing the onset of dormancy:
- Temperature: Sustained exposure to temperatures between 5 °C and 12 °C initiates metabolic slowdown.
- Photoperiod: Day lengths under 12 hours suppress hormonal cues that normally promote egg production.
- Host presence: Decline in host activity or accessibility reduces blood meals, prompting adults to conserve energy.
- Humidity: Relative humidity below 50 % accelerates dehydration, reinforcing the decision to remain inactive.
Physiologically, dormant adults exhibit reduced locomotor activity, diminished feeding attempts, and altered hormone levels, notably decreased juvenile hormone and increased diapause‑inducing factors. Energy reserves shift from glycogen to lipid stores, allowing survival for several months without a blood meal. In species such as Ctenocephalides felis (cat flea) and Pulex irritans (human flea), the dormant period can extend from late autumn through early spring, resuming activity when temperatures rise above 15 °C (59 °F) and day length exceeds 14 hours.
Geographic variation modifies the timing. In subtropical regions, where temperature fluctuations are modest, dormancy may be absent or limited to brief cold spells. Conversely, in high‑latitude areas, the dormant phase can begin as early as September and persist until May, coinciding with prolonged cold periods.
The cessation of reproductive activity during dormancy also includes a halt in egg laying; females retain mature eggs in their ovaries until favorable conditions return. Upon reactivation, mating, blood feeding, and oviposition resume rapidly, often within 24 hours of exposure to suitable environmental cues.
Understanding these triggers assists in predicting flea population surges and informs timing for control measures, such as the application of insecticides before the end of the dormant interval to target emerging adults.