Until now the insect endoskeleton has been largely ignored. Even the most detailed thoracic studies show endoskeletal structures as nameless shapes or beautifully drawn unnamed features. When names were given, they were few, generalized, and over-used, because early morphologists examined few specimens and applied names to structures in other insects with the tacit assumption that all insects are the same. Such studies as those of Snodgrass (1947) on Blattaria, and Comstock (1924) on Orthoptera and Thysanura, underappreciated the value of the endoskeleton, because its apparent simplicity in these insects suggests it lacked enough characters to be of systematic interest. This preliminary study had two goals. To determine if the structures of the heteropteran thoracic endoskeleton might be useful in systematic work (and at what systematic levels), and to standardize nomenclature of those structures. Both goals were reached: These structures are systematically useful at several taxonomic levels; and their nomenclature has been standardized, thus making comparative studies feasible.