This study shows that citrus oils have repellent efficacy
against B. germanica, P. americana and P. fuliginosa. The repellent
efficacy was largely due to their main monoterpene
component, limonene, but other major components may also
contribute to the repellent efficacy of these oils. Further studies
examining whether these minor monoterpene components
act additively or synergistically on various cockroach species
are in progress.