The nature and properties of a variety of plasmids are described that facilitate the construction of baculovirus vectors for expression of one or more heterologous genes. The plasmids are designed for use with Autographa californica nuclear polyhedrosis virus, AcMNPV, as a vector for protein production in insect cells and/or insect larvae. Several plasmids described here facilitate the simultaneous insertion and expression of two different genes. Some vector systems allow high and equal levels of transcription of both genes while others employ two different promoters for differential transcription. Four of the plasmids described here are designed for expression of both the viral polyhedrin-encoding gene and a heterologous gene. Such recombinants form polyhedral occlusion bodies which serve as visible markers of recombination and facilitate oral infection of insect larvae for mass-scale protein production. A synthetic promoter with a unique sequence can be used at a variety of sites in the viral genome and avoids sequence duplication. A series of plasmids are also described that supply an N terminus with an efficient translational initiation signal and convenient multiple cloning sites in the three different translational reading frames. The modular nature of all the constructs allows the use of other promoters with different temporal regulation to be utilized in the construction of additional plasmids for customized expression work.