The present work was directed to study the possibility of using ultrastructure and electrophysiological techniques to distinguish all the sensory sensilla on the antennae and tarsi of female S. littoralis, as a trail to understand the insect chemical communication system. Relatively little is still known about the types, location and functions of S. littoralis sensory organs. The sensory organs on the antennae and on the tarsi of female S. littoralis were visualized by scanning and transmission electron microscopy. The surface of the tarsus is covered with scales overlapped together and is provided with sense sensilla that found on the ventral and lateral surface of the tarsus. Two basic types of sensilla were found on the tarsus of the prothoracic legs, the mechanosensory sensilla (squamiformia) that have one neuron, and the contact chemosensory sensilla (trichodeum, chaeticum and styloconica) that are multimodal receptors and have five neurons. While three basic types of sensilla were identified on the antennae, mechanosensory sensilla (squamiformia, chaeticum, auricillica and coeloconia), chemosensory sensilla as on the tarsus (styloconica, basiconica and small chemoreceptor pag) and olfactory sensilla (trichodeum) that have many neurons. The identification of the different types of sensilla on the tarsus and antenna will serve for electrophysiological studies, which can be made on them to clarify their functions.
Key words: S. littoralis, Sense organs, SEM, TEM, Electrophysiology, Tip recording technique.