wind-sensitive cercal receptor/giant interneurone system of the locust, Locusta migratoria. I. Anatomy of the system

The cerci bear hair sensilla of two basic types (a) filiform hairs, which emerge from a cuticular pit, are flexibly mounted, and are sensitive to wind and to mechanical displacement; and (b) bristle (or trichoid) hairs, which originate directly from the surface of the cercus, and are less flexibly mounted. The axons of neurones innervating these hairs group together into successively larger bundles before joining the cercal nerve which runs to the terminal ganglion. The cercal receptor/giant interneurone system of Locusta is compared to those of other orthopteroid insects, with special attention to the origin and evolution of giant interneurones.