Abstract Based on our previous finding that PIM (phenyl-imidazolyl-metyra-pon; 2-(1- imidazolyl)-2-methyl-1-phenylpropan-1-one, 1) is a strong inhibitor of ecdysone 20- monooxygenase (IC 50= 7.89× 10− 7 M) from the fleshfly, Neobellieria bullata (Parker) and has also a good toxic action in vivo against this insect, 17 imidazole and 1, 2, 4-triazole analogues of metyrapone were synthesized and evaluated for their action against N. ...