A pre-attachment aggregation pheromone in the adult metastriate tick Hyalomma dromedarii Koch (Acarina: Ixodidae).

In vitro investigation demonstrates the existence of pheromone-regulated movement in the metastriate tick H. dromedarii before host contact. Males exhibit significant assembly to material of females. The palps, not Haller's organ, are essential for pheromone detection. The material is soluble in water, not in ether, benzene, or acetone and it is relatively stable to heat and cold.