Methods are given that were used routinely for 2 years to produce up to a gram of purified regular mosquito iridescent virus (RMIV) per week from larval Aedes taeniorhynchus (Wiedemann). Achieving maximum net virus production with a minimum of manpower required effective transmission of the virus during exposure, minimal larval mortality both during exposure and during post-exposure rearing, and virus purification procedures that wasted a minimum of virus. Transmission rates of about 10% (calculated on the basic of number of larvae exposed) were achieved by 24 hr per os exposures of groups of 2500 second stage larvae to 50 larval equivalents of freshly triturated inoculum in 8 oz capacity waxed paper cups. Although infected larvae were smaller than the apparently uninfected larvae, an average of 58.9 ug of virus per infected larva was recovered by differential centrifugation and sucrose density gradient centrifugation. Virus constituted at least 9.3% of the dry weight of the average infected larva.