Western flower thrips (Frankliniella occidentalis), is a major pest of greenhouse tomato crops because it is a primary vector of tomato spotted wilt virus (TSWV). The virus is propagatively transmitted and viruliferous thrips are able to transmit the virus throughout their adult life. The predatory mite Amblyseius cucumeris is an effective option for managing western flower thrips, but many producers are not convinced that biological control can effectively reduce virus risk. To compare the efficacy of different thrips management strategies for management of TSWV, tomatoes were subject to one of three treatments: 1) biological control based on weekly releases of A. cucumeris at a commercially-recommended rate; 2) a single chemical treatment with ConserveŽ, a spinosad formulation, and 3) no treatment. Virus may be introduced into a greenhouse either by infected plant material or by the influx of infected thrips. Therefore, TSWV was introduced into our greenhouses either by: 1) a single release of viruliferous adult thrips into the crop, or 2) starting with 20% ratio infection rate of the tomato crop. Each treatment combination was applied to a greenhouse containing 80 tomato plants which were grown for eight weeks. Total crop yield and percentage of infected plants at the end of each turn were the measures of efficacy. TSWV incidence did not differ significantly between the biological and chemical control methods. Total yield was consistent with final percent plant infection. We conclude that biological control may be able to provide adequate protection from TSWV in commercial greenhouse tomato crops.