Why don't all domestic bedbugs bite? - briefly
Only fertilized females need a blood meal to produce eggs, so they bite humans; males, immature stages, and unmated females either feed on other hosts or remain unfed. Therefore, a domestic infestation often contains many bedbugs that never bite people.
Why don't all domestic bedbugs bite? - in detail
Bedbugs (Cimex lectularius) require a blood meal to develop and reproduce, but not every individual in a household will bite a human host. Several biological and environmental factors determine whether a particular insect will feed.
Adult females are the only sex that must obtain blood to produce eggs; unmated males and females that have already completed a reproductive cycle may remain unfed for days or weeks. Nymphal stages also need blood, yet each instar can survive a period without a meal, especially when ambient temperature and humidity are favorable. Consequently, a population may contain individuals that have recently fed, others that are in a pre‑feeding state, and some that are temporarily dormant.
Physiological condition influences feeding propensity. Bedbugs with low energy reserves, dehydration, or recent exposure to sublethal insecticides may suppress host‑seeking behavior. Conversely, well‑nourished insects exhibit stronger attraction to carbon‑dioxide, heat, and host odor cues.
Genetic variation within a colony can affect host preference. Some strains display a stronger inclination toward human blood, while others are more opportunistic, feeding on pets, birds, or rodents when available. This diversity results in a mixed pattern of biting activity in domestic settings.
Environmental parameters also play a role. Temperatures between 24 °C and 30 °C and relative humidity above 50 % accelerate metabolism and increase host‑searching activity. In cooler or drier conditions, bedbugs reduce movement and may avoid feeding altogether.
Finally, recent feeding history determines the immediate need to bite. After a successful blood meal, a bedbug can survive several weeks without another, during which time it does not seek a host. This interval creates periods when the household experiences no bites despite the presence of insects.
Key determinants of non‑biting behavior:
- Sex and reproductive status (only blood‑feeding females need regular meals)
- Developmental stage (nymphs versus adults)
- Nutritional and hydration condition
- Genetic predisposition toward host species
- Ambient temperature and humidity
- Time elapsed since the last blood meal
Understanding these factors clarifies why a domestic infestation may not produce uniform biting incidents, even when the insects are present throughout the residence.