The antenna of the final instar larva of Tenebrio molitor has three segments. The reduced third (terminal) segment bears a large trichoid sensillum, four uniporous peg sensilla, one blunt tipped peg sensillum, and one papillate sensillum. The second segment bears a very large multiporous placoid sensillum, three uniporous peg sensilla, one blunt-tipped peg sensillum, and one papillate sensillum. The numbers and arrangement of these sensilla are usually stereotyped, but variations occur.The trichoid sensillum is a long, thin, unsocketed, aporous hair. It is innervated by two (sometimes one) bipolar neurones and has five sheath cells. The three sheath cells which distally delimit the large sensillar sinus have extremely elaborate microvillate inner borders. The uniporous peg sensillum is a short, stout, socketed peg with a single terminal pore. It is innervated by two to six (usually six) bipolar neurones. The dendrite from one of these always ends as a tubular body in the base, while the dendrites from the others extend to the tip of the peg. This sensillum has a small sensillar sinus and only four sheath cells. The inner sheath cell of both types of sensilla forms a cylindrical, nonlapped sleeve around the dendrite bundles.

Each antenna of a final instar Tenebrio molitor larva has two blunt-tipped pegs and two papillate sensilla. The former are short pegs with fluted cuticle and a terminal moulting pore and are set in deep sockets. Two large microtubule-filled dendrites fill a dense dendritic sheath within the peg; below the base of the peg they are joined by a lamellate dendrite and a dendrite resembling a scolopidial cilium. There are four accessory cells, the innermost resembling a scolopale cell. This sensillum may be thermo- and hygro-receptive.Superficially the papillate sensillum is radially symmetrical with a central zone of small cuticular papillae surrounded by one or two rings of smooth cuticle. Three or four dendrites (of five) end under a turret of longer papillae at the center of the papillate cuticle. Fine pores from the dendritic canal extend to the surface between the papillae. One or two dendrites, one of which may be lamellate, end well below the end organ. There are five accessory cells. The sensillar and ciliary sinuses are large and the bounding membranes of the sheath cells highly elaborated. The function of this sensillum is uncertain.

The third (terminal) segment of the antenna of the final instar larva of Tenebrio molitor contains a single, unusually positioned and attached chordotonal sensillum. This sensillum consists of four cells: a microtubule-filled attachment cell anchoring the sensillum in the basement membrane-like extracellular matrix of the segment, a scolopale cell containing a strongly developed fibrous scolopale ensheathing the dendrite, a typical type I bipolar neuron, and a basal glial cell. The ultrastructure of this sensillum and its relationships to other antennal structures are described and compared with other chordotonal sensilla reported in the literature.