Comparative Study of the Pygidial Defensive Systems of Carabid Beetles

Investigations were made on the pygidial defensive components and gland morphologies of 132 species in 60 genera of carabid beetles. Components so far detected may be divided into six groups, : (1) formic aicd, (2) methacrylic, tiglic and/or ethacyrlic acids, (3) other acids, such as n-butyric, iso-butyric, iso-valeric, iso-crotonic, angelic and several other acids (4) m-cresol, (5) benzoquinones with one chamber, (6) benzoquinones with two chambers. Gland types so far observed may be divided into three types : (1) spherical lobes which produce fatty acids, (2) elongated lobes which produce m-cresol, (3) long thick lobes which produce benzoquinones. There were also three different kinds of fatty-acid-producing glands at the points of entry of the collecting canals to the resevoris. The same genera, or at least the same subgenera, shared similar components and gland types.