Fluorescent structures in the metathorax of Aphrophora and Philaenus. Externally visible fluorescence at the right (A) and left (B) lateral pivot of the thoraco-coxal joints of the hind legs of Aphrophora. Bright field images and those illuminated with ultraviolet light (see Methods) at the same position and focal plane are superimposed. (C) Ventral view of the internal metathorax of Philaenus after removal of the ventral cuticle and thoracic muscles. The pleural arches linking the coxae with the hinges of the hind wings are outlined with dashed lines. Part of each pleural arch fluoresces bright blue.