Why do fleas bite children but not adults? - briefly
Fleas are drawn to the higher body temperature, greater carbon‑dioxide emission, and softer, thinner skin that characterize young children, whereas adults usually present lower levels of these attractants and thicker skin that reduces flea attachment.
Why do fleas bite children but not adults? - in detail
Fleas are attracted to the carbon dioxide, heat, and movement produced by a host. Children emit relatively higher levels of carbon dioxide per body weight because of faster metabolism, creating a stronger chemical cue for the insects. Their skin temperature is often slightly higher than that of adults, especially during active play, enhancing thermal detection.
Sweat composition differs between age groups. Children’s sweat contains greater concentrations of certain amino acids and fatty acids that serve as feeding stimulants for fleas. These substances are detected by the insects’ chemoreceptors, prompting them to bite.
Hair density and length also influence accessibility. Younger individuals typically have finer, less dense hair, allowing fleas easier penetration to the skin surface. In contrast, thicker adult hair creates a physical barrier that reduces bite frequency.
Behavioral factors contribute as well. Children spend more time on the ground, engaging in activities that increase contact with infested environments such as carpets, bedding, and outdoor grass. This heightened exposure raises the probability of flea encounters.
The combination of physiological signals, chemical attractants, hair characteristics, and lifestyle patterns explains the preferential biting of younger hosts over mature ones.