Microscopic Structure of Mouth Parts Sensillae in the Fifth Instar Larvae of Eri Silkworm, Philosamia ricini (Lepidoptera: Saturniidae)

Scanning electron microscopic studies revealed the presence of various types of sensillae on the mouth parts of Vthinstar larva of Philosamia ricini. The mouth parts of P. ricini belong to chewing types and composed of labrum, mandible, labium and maxilla. The three pair of long and short trichoid sensilla present on dorsal side around the groove of labrum. Dorso lateral margine of labrum consist of two pairs of sensilla trichoidea I and II (ST-I, II). On lateral side of mandible, ST-I and sensilla chaetica (SCH) are scattered while, some campaniform sensilla (CS) are present on the base of teeth. The sensilla trichoidea with or without basal ring present on maxillary palp in association with sensilla basiconica. The tip of palp contain sensilla styloconica while, short microtrichia, sensilla baiconica and sensilla styloconica observed on the stipes. Labial palp are tough and stout containing large and short trichoid sensilla. Various minute slite-like structures arranged in V shaped pattern, partially separated basal ring from bulbus base ST-I of labial palp. On the ventral side of mentum two layer of microtrichia MT-I and MT-II are overlapped each other. In the Vth instar larvae of P. ricini, spinneret bulges out from prementum and bears a pair of horns on the tip.