A population survey of thrips and of whitefly was conducted on eggplants and cucumbers in greenhouses with and without naturalenemies, Nesidiocoris tenuis and Amblyseius swirskii. Density of thrips and whitefly on cucumbers had been below the control threshold density (one individual per leaf) during survey period. Similarly, thrips density was below the control threshold density on eggplants in greenhouse with N. tenuis and A. swirskii. On the other hand, whitefly densities on eggplants were temporarily beyond the control threshold level. Nevertheless, no substantial economic loss was observed. Pesticide use in greenhouses with N. tenuis and A. swirskii was less than that in greenhouse without these natural enemies.