The present invention relates to a method of combating animal pests which comprises contacting the animal pests, their habit, breeding ground, food supply, plant, seed, soil, area, material or environment in which the animal pests are growing or may grow, or the materials, plants, seeds, soils, surfaces or spaces to be protected from animal attack or infestation with a pesticidally effective amount of at least one 6-halogeno[1,2,4]triazolo[1,5-a]-pyrimidine of the general formula (I), wherein X, R1, R2, R3 and R4 are as defined in claim 1 and/or the agriculturally useful salts thereof.