What characteristic is associated with heavy infestations of bedbugs?

Heavy infestations of bedbugs are often associated with a foul odor. This odor is typically a result of the aggregation of many bedbugs in one area, which can produce a musty scent due to their biological processes and the presence of their droppings and shed exoskeletons.

When there is a significant population of bedbugs, the accumulation of these factors contributes to a distinctive smell that can often be a telltale sign of an infestation. This is particularly relevant as it helps pest control operators identify the extent of an infestation even before visually spotting the insects themselves.

The other options do not apply to heavy infestations in the same way; for instance, while bedbugs can exhibit an active behavior, it is not a reliable characteristic of heavy infestations. Similarly, their color is typically brownish or reddish rather than bright, and they are relatively small, so size also does not denote an infestation’s severity. The olfactory cue provided by the foul smell is a more consistent indicator.