Abstract: The compounds of formula I are described ##STR1## wherein Hal is halogen, such as fluorine, chlorine, bromine or iodine;R.sub.1 is hydrogen, C.sub.1 -C.sub.6 alkyl or C.sub.3 -C.sub.7 cycloalkyl;R.sub.2 is hydrogen, C.sub.1 -C.sub.6 alkyl or C.sub.3 -C.sub.7 cycloalkyl, andR.sub.3 is hydrogen or C.sub.1 -C.sub.6 alkyl,for use in a method of controlling fleas in domestic animals, especially in dogs and cats, wherein systemic administration is preferred. The compounds of formula I are administered in an amount effective against fleas via the digestive tract or via the blood of the host animal and thus systemically to the domestic animal, especially the dog or the cat.