Why do bedbugs not bite everyone in a household? - briefly
Bedbugs feed only on hosts that emit strong heat, carbon‑dioxide, and specific skin chemicals, so individuals with weaker cues or partial resistance may escape bites. Limited feeding slots and competition among the insects also leave some household members untouched.
Why do bedbugs not bite everyone in a household? - in detail
Bedbugs feed selectively because their host‑selection process depends on physiological and behavioral cues that differ among individuals.
First, skin temperature and carbon‑dioxide output vary with activity level, metabolism, and body size. Warmer skin and higher CO₂ concentrations attract the insects, so people who are more active, have higher basal metabolic rates, or generate more heat are more likely to be detected.
Second, chemical signals on the skin influence feeding. Sweat contains compounds such as lactic acid, fatty acids, and ammonia; their concentrations are affected by diet, genetics, and hygiene. Individuals with higher levels of these attractants present a stronger olfactory signal, while others emit weaker cues that may go unnoticed.
Third, the presence of protective skin bacteria can mask or modify the odor profile. Certain microbial communities produce volatile substances that repel or confuse bedbugs, reducing the likelihood of a bite.
Fourth, previous exposure can induce a defensive response. Repeated feeding on the same person may lead the insect to develop a learned preference for that host, leaving other occupants less targeted.
Fifth, physical barriers limit access. Clothing, blankets, or sleeping positions that conceal exposed skin reduce the chance of contact.
Key factors summarised:
- Thermal and respiratory cues: higher body heat and CO₂ attract more bites.
- Skin chemistry: elevated lactic acid, fatty acids, and ammonia increase attractiveness.
- Microbiome composition: certain bacterial strains emit repellent volatiles.
- Host habituation: insects may focus on a familiar host after initial feeding.
- Physical coverage: clothing and bedding reduce exposed surface area.
Understanding these variables explains why some household members experience frequent bites while others remain largely untouched.