What contributes to the population expansion of bed bugs?

The population expansion of bed bugs is significantly influenced by the availability of food from humans. Bed bugs are ectoparasites that primarily feed on blood, and humans are their primary hosts. The presence of humans in close quarters provides a consistent and accessible food source, which fuels their reproduction and increases their populations. As they can reproduce rapidly, when conditions are favorable—such as an ample supply of human hosts—bed bug populations can grow quickly.

While environmental temperature changes can impact bed bug behavior and development, the direct relationship between human proximity and the availability of blood makes the presence of humans the most crucial factor for their population expansion. The other choices do not play as significant a role in the specific context of bed bug proliferation.