From dawn to dusk, bed bugs remain mostly in their harborages. Understanding their movements after the lights go out can provide useful insight.
Running on Empty.
Bed bugs are mostly nocturnal, but will adapt to the sleep cycle of their host. For example, if a person works the night shift and sleeps during the day, the bugs will adjust and feed during daylight hours. Hungry bed bugs may feed regardless of the time of day — an occupational hazard experienced at times by service technicians. Hungry bed bugs also tend to move around more than satiated bugs, presumably in order to locate a food source. However, if host absence is prolonged (as might occur in a vacant apartment), their search activity may be reduced in order to conserve energy.
Video recordings of adult bed bugs in laboratory test arenas showed they can travel over 16 feet in five minutes, even in the absence of host-orienting cues. Given that the hunt for a meal could last for hours, it is understandable that wandering bed bugs can sometimes end up in suitcases and other belongings.
Recently we had an opportunity to study bed bug movement in a heavily infested house and an apartment. Interceptor-style (pitfall) monitors were placed in several locations, near and far from where occupants slept and bugs were observed. Most of the pitfall monitors were placed along baseboards and in corners of rooms — rather than beneath bed and furniture legs — which is more typical in commercial practice.
To further assess bed bug mobility, groups of bugs in various locations were marked with paint. Different colors were used to distinguish where the bugs initially resided vs. where they were subsequently found.
Each dwelling was re-inspected a week after the bugs were marked and monitors installed. The number of bed bugs captured in each monitor was recorded along with where marked bugs were found relative to their previous location.
These tests clearly reinforce that bed bugs move around during their nighttime forays.
Bed bugs congregate near sleeping or stationary hosts, especially during early stages of infestation. As populations grow larger, they often disperse beyond the usual beds, sofas and recliners to other areas of refuge. Why this happens is still under investigation. One theory is that bed bug dispersal is initiated by adult females seeking to avoid repeated, potentially harmful mating attempts by males. Another hypothesis is that dispersal has little to do with “fleeing” females, and has more to do with refuge availability. Rather, as numbers increase and harborages near hosts become occupied, bed bugs (comprised of all life stages) gradually form new clusters farther away.
Another question researchers are attempting to answer is whether blood-seeking bed bugs return to their former harborage locations.
Bed bugs probably feed at least weekly in the presence of a host.