Uniform Size Particle Barrier: A Physical Exclusion Device Against Subterranean Termites (Isoptera: Rhinotermitidae)

Workers of the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar), were tested for their abilities to penetrate barriers of ground coral particles 5 cm thick. Each barrier was composed of one of 13 particle sizes, ranging from 0.5 to 4.0 mm in diameter. C. formosanus penetrated the least through particles of 1.70-2.36 mm in size, and a wider size range of particles (1.00-2.36 mm) excluded penetration by R. flavipes. When several size ranges were uniformly mixed, the resultant barriers composed of particles in the 1.18-2.80 mm size range effectively prevented penetration by both termite species.