4-Haloalkenyl-2,3,5,6-tetrafluorobenzyl alcohols of formula (III): ##STR1## are intermediates to insecticidally active fluorobenzyl esters of formula (I): ##STR2## wherein X represents the residue of any carboxylic acid of formula X-COOH which forms an insecticidally active ester with a 3-phenoxybenzyl alcohol, and R, R.sup.6 and R.sup.7 are each selected from hydrogen, halogen and alkyl of up to four carbon atoms, provided that at least one of R, R.sup.6 and R.sup.7 represents halogen, and further provided that R and R.sup.6 are not both bromine when R.sup.7 is hydrogen.