Recombinant baculoviruses have been used to produce foreign proteins and have the potential to be safe, efficacious insecticides. Isolation of recombinant virus is usually by plaque phenotype. Typical recombination rates are less than 1%, thus requiring time consuming inspection of hundreds of individual plaques. A method of generating recombinants is described which requires less time than current protocols and frequently produces recombinants at rates exceeding 30%. This protocol employs liposome-mediated transfection, reduced post-transfection incubation times, linearized parental virus which produces occlusion positive plaques in clones of the parental genotype, and colorimetric detection of recombinants. This protocol allows the initial, and frequently the final, isolation of recombinants in 7 days. (Copyright (c) 1992 Elsevier Science Publishers B.V.)