PIERCING OR BITING INSECTS POISONOUS TO MAN HEMIPTERA Several families of the true bugs include forms which, while normally inoffensive, are capable of inflicting painful wounds on man. In these, as in all of the Hemiptera, the mouth-parts are modified to form an organ for piercing and sucking. This is well shown by the accompanying illustration (fig. 16). The upper lip, or _labrum_, is much reduced and immovable, the lower lip, or _labium_, is elongated to form a jointed sheath, within which the lance-like mandibles and maxillæ are enclosed. The mandibles are more or less deeply serrate, depending on the species concerned. [Illustration: 16. Beak of hemipteron.] The poison is elaborated by the salivary glands, excepting, possibly, in _Belostoma_ where Locy is inclined to believe that it is secreted by the maxillary glands. The salivary glands of the Hemiptera have been the subject of much study but the most recent, comprehensive work has been done by Bugnion and Popoff, (1908 and 1910) to whose text the reader is referred for details. The Hemiptera have two pairs of salivary glands: the _primary gland_, of which the efferent duct leads to the salivary syringe, and the _accessory gland_, of which the very long and flexuous duct empties into the primary duct at its point of insertion. Thus, when one observes the isolated primary gland it appears as though it had efferent ducts inserted at the same point. In _Nepa_ and the _Fulgoridæ_ there are two accessory glands and therefore apparently three ducts at the same point on the primary gland. The _ensemble_ differs greatly in appearance in different species but we shall show here Bugnion and Popoff's figure of the apparatus of _Notonecta maculata_, a species capable of inflicting a painful bite on man (fig. 17). [Illustration: 17. Salivary glands of Notonecta maculata. After Bugnion and Popoff.] [Illustration: 18. Pharyngeal syringe or salivary pump of Fulgora maculata. After Bugnion and Popoff.] [Illustration: 19. Heteroptera, (_a_) Melanolestes picipes; (_b_) Notonecta undulata; (_c_, _d_) Aradus robustus (_c_) adult, (_d_) nymph, much enlarged; (_e_) Arilus cristatus; (_f_) Belostoma americana; (_g_) Nabis (Coriscus) subcoleoptratus, enlarged; (_h_) Cimex lectularius, (_i_) Oeciacus vicarius, much enlarged; (_j_) Lyctocoris fitchii, much enlarged. After Lugger.] Accessory to the salivary apparatus there is on the ventral side of the head, underneath the pharynx, a peculiar organ which the Germans have called the "Wanzenspritze," or syringe. The accompanying figure of the structure in _Fulgora maculata_ (fig. 18) shows its relation to the ducts of the salivary glands and to the beak. It is made up of a dilatation forming the body of the pump, in which there is a chitinous piston. Attached to the piston is a strong retractor muscle. The function of the salivary pump is to suck up the saliva from the salivary ducts and to force it out through the beak.