Why do some fleas bite while others do not? - briefly
Female fleas need blood to mature eggs, so they bite; male fleas obtain sufficient nutrients from host secretions and rarely puncture the skin. Some species that parasitize rodents exhibit reduced biting behavior because their life cycle relies less on blood meals.
Why do some fleas bite while others do not? - in detail
Fleas exhibit a spectrum of feeding behaviors that depends on species, developmental stage, and physiological adaptations.
Adult members of the genera Ctenocephalides and Xenopsylla possess mouthparts designed to pierce skin and inject saliva containing anticoagulants; this enables them to obtain blood from mammals and birds. In contrast, larvae lack such structures and survive on organic debris, fungal spores, and adult excrement, so they never bite.
Among adults, females require a blood meal to mature eggs, prompting more aggressive host‑seeking activity. Males can survive on occasional blood intake but often display reduced biting frequency.
Factors influencing whether a flea will bite include:
- Species‑specific morphology of the proboscis and salivary glands.
- Presence of sensory receptors that detect host heat, carbon‑dioxide, and movement.
- Hormonal cues linked to reproductive cycles that trigger feeding urges.
- Environmental conditions—temperature above 15 °C and relative humidity between 70 % and 80 %—that increase metabolic demand and activity levels.
Genetic variation determines the expression of enzymes such as apyrase and anticoagulant proteins; species lacking these compounds are unable to sustain blood feeding and thus avoid biting.
Consequently, only those flea taxa equipped with appropriate anatomical features, reproductive drives, and favorable environmental settings engage in hematophagy, whereas other life stages or species remain non‑biting.