Greenhouse production systems typically involve growing multiple crop types simultaneously, including ornamentals and vegetables. Therefore, greenhouse producers commonly deal with multiple pest complexes. Two important insect pests of greenhouse-grown horticultural crops are fungus gnats (Bradysia spp.) and western flower thrips (Frankliniella occidentalis). A plant protection strategy that can be used to manage both pests is biological control. The rove beetle (Dalotia coriaria) and insidious flower bug (Orius insidiosus) are generalist predators commercially available for use in greenhouse production systems targeting fungus gnats and the western flower thrips. This article describes the biology, behavior, ecology, and role of both natural enemies in greenhouse production systems, and discusses the direct and indirect effects of pesticides (insecticides, miticides, and fungicides) on D. coriaria and O. inisidiosus.