Novel pesticides of formula (I) ##STR00001## wherein the substituents, R, R.sub.1, R.sub.2, R.sub.2', T, U, X and Y are as defined in claim 1, are described. Also described are compositions suitable for use as parasiticides comprising those compounds as active ingredient and to methods of controlling parasites that are based on the administration of those compounds or compositions, and to the use of the said compounds and compositions in a method of controlling parasites and in the manufacture of pesticides for use against parasites. Also described are intermediates of formula (XX) ##STR00002## wherein R.sub.1, R.sub.2, R.sub.2', T, U, X and Y are as defined in claim 1; and Hal is halogen. The latter also exhibit parasiticidal activity and are suitable for the preparation of the compounds of formula (I).