It is now well established that Termites have a means of communication by sounds. The individuals have a peculiar way of jerking themselves, as has been frequently noticed by observers of the Insects; these convulsive movements may possibly be connected with the production of sound, which may perhaps be evoked by contact between the back of the head and the pronotum; the exact mode by which the sounds are produced is not, however, known. The existence of an auditory organ in the front tibia has been demonstrated by Fritz Müller,[283] and we reproduce (Fig. 227) one of his figures. The structure seems to {359}be in plan and position similar to the ear of Locustidae, though much less perfect. [Illustration: FIG. 228.—Wings of Termites: A, _Termes lucifugus_; B, _Hodotermes brunneicornis_; C, _Culotermes nodulosus_. (After Redtenbacher: B and C diagrammatic.) III, V, VII, homologous areas and nervures according to Redtenbacher. 1, Costal; 2, subcostal; 3, median; 4, submedian nervures according to Hagen.] The wings of Termitidae are not like those of any other Insects; their neuration is very simple, but nevertheless the wings of the different forms exhibit great differences in the extent to which they are made up of the various fields. This is shown in Fig. 228, where the homologous nervures are numbered according to the systems of both Hagen and Redtenbacher. The area, VII, that forms the larger part of the wing in C, corresponds to the small portion at the base of the wing in B. The most remarkable feature of the wing is, however, its division into two parts by a suture or line of weakness near the base, as shown in Fig. 225. The wings are used only for a single flight, and are then shed by detachment at this suture; the small basal portion of each of the four wings is horny and remains attached to the Insect, serving as a protection to the dorsal surface of the thorax. The nature of the suture that enables the Termites to cast their wings with such ease after swarming is not yet understood. There are no true transverse veinlets or nervules in Termites. Redtenbacher suggests[284] that the transverse division of the wing at its base, as shown in Fig. 225, along which the separation of the wing occurs at its falling off, may have arisen from a coalescence of the subcostal vein with the eighth concave vein of such a wing as that of Blattidae. The same authority also informs us that the only point of resemblance between the wings of Termitidae and those of Psocidae is that both have an unusually small number of concave veins.