The bed bug,Cimex lectularius, aggregates under filter paper disks stained by engorged adults. A multiple choice assay was used to determine which sensory structures mediate aggregation and the effect of antennectomy on movement, orientation and aggregation behavior relative to the location of a stained disk. In the first, two-factor experiment, treatments included lighting vs. darkness, and physical manipulations of five kinds. Bed bugs were left intact, blinded, or surgically altered by removal of probosci, the distal two antennal segments (partial antennectomy), or all four segments (complete antennectomy). Treated groups of bed bugs were released into individual arenas with one stained disk and seven unstained disks. The final position of each insect was recorded after four hours. Aggregation under stained disks was unaffected by lighting, blinding, proboscis removal and partial antennectomy treatments. However, complete antennectomy significantly reduced aggregation (3.1% ± 6.4%) compared to intact bugs (89.7% ± 7.5%). In a second experiment, movement and orientation by intact, partial and complete antennectomy treatments were measured with time lapse photography. Neither partial nor complete antennectomy affected walking speed, straightness of the path, direction of movement or frequency of disk encounters in each arena. However, there was a significant reduction in the percent of encounters that resulted in arrestment under the stained disk by complete antennectomy treatments (2.7% ± 3.6%) compared to intact bugs (50.1% ± 26.5%). These findings suggest aggregation is an arrestment response, which is mediated by direct contact of the basal segments of the antennae with stained disks.