The anatomy of the head-capsule and mouthparts ofDysdercus fasciatusSign. (Pyrrhocoridae, Hemiptera)

Summary The head of Dysdercus fasciatus Sign. is prognathous and preserves the generalized heteropterous orientation of the mouthparts. Its dorsal surface is composed of occiput, vertex, frontoclypeus, and the mandibular plates; while the ventral surface is formed by the maxillary plates, which are medially fused with the hypostoma. The lateral surfaces consist of the parietal plates, comprising gena and vertex, together, lying between the dorsal and the ventral surfaces on either side. A comprehensive account is given of the internal structures, viz. the sucking pump, the salivary apparatus, the hypopharynx, the maxillary and mandibular pouches and bristle sacs, the maxillary and mandibular stylets and levers, with particular reference to their functions. The sequence of movements made by the stylets in the artificial media (3% agar and 10% sucrose) is described and compared with the mode of penetration of the stylets into the cotton plants.