Sensillar structures of the antennal pedicel are investigated in Reduviidae and Pachynomidae. The cave organ, a presumably chemoreceptive structure, previously reported only for haematophagous Triatominae, is described here also for representatives of Peiratinae, Reduviinae and Stenopodainae. The systematic implication of the occurrence of this sensillar structure is discussed. Further, four sclerites located in the membrane between pedicel and preflagelloid are described and used as landmarks for the recognition of individual trichobothria in Reduviidae and Pachynomidae. Characters of the trichobothrial socket are studied and discussed systematically. Homology of the distalmost trichobothrium of Reduviidae with the single trichobothrium in Pachynomidae is proposed. This hypothesis is based on the structure of the cuticle surrounding the trichobothria and on the trichobothrial position relative to the four sclerites of the pedicello-flagellar articulation. The single trichobothrium present in most nymphs corresponds to the distalmost trichobothrium in adult Reduviidae in position and structural detail. A reasonable hypotheses on the homology of individual trichobothria of the proximal row or field seen in most Reduviidae can so far only be formulated for Peiratinae.