What induces bed bugs to start searching for human hosts?

The behavior of bed bugs seeking out human hosts is primarily influenced by the presence of carbon dioxide (CO2) that is exhaled during breathing. Bed bugs are highly attuned to environmental cues that signal the presence of a potential host, and CO2 is a significant indicator that a warm-blooded animal, such as a human, is nearby.

When a person exhales CO2, it creates a chemical gradient that bed bugs can sense, prompting them to move towards the source of this gas. This chemical attraction is crucial for their survival and feeding, as bed bugs are obligate ectoparasites that rely on blood meals to grow and reproduce.

While the heat from the body and movement can also attract bed bugs to some degree, it is the CO2 that plays a key role in their host-seeking behavior because it signals the presence of a live host. Light, on the other hand, has little impact on bed bug attraction as they are primarily nocturnal and tend to avoid light sources. Thus, the presence of CO2 from breathing is a crucial factor that induces bed bugs to start their search for a meal.