Abstract: The mating behaviour of Haemaphysalis longicornis consisted of 7 stages. Bioassay suggested that male response was regulated by the sex pheromone secreted by females. Blocking up female fovea, male response was inhibited; while topical application of 2,6-DCP or extract of female foveal glands could restore it. A highest level of 2,6-DCP content (11.12ng/individual) was reached during the 1st～2nd day after attachment when analysis by GC. The amounts of 2,6-DCP declined on the 3rd～5th day after attachment just before mating, but maintained at a relatively constant level. After mating, it declined singificantly and became undetectable after engorgement.

Key words: Haemaphysalis longicornis, 6-DCP, mating behaviour