In the framework of studies on the possible use of dichlorvos (DDVP) in flour mills, the authors investigated the effects of various parameters (such as concentration of the DDVP solution to be used, temperature, location of the samples, different kinds of samples and packages) on the formation of DDVP residues on milling products. It was found that a concentration of 0.6 ml of DDVP-50/m3 and temperatures ranging from 18 degrees to 22 degrees C are particularly suited for insect control. Under these conditions, the DDVP residues on the samples were degraded within a period of 2--4 weeks, according to the kind of product. Uncovered foods shall not be present in rooms where DDVP is being applied. In virtue of the present findings, DDVP is recommended for use in flour mills.