Cryptic mealybug (CMB), Pseudococcus cryptus, is a serious scale pest on citrus, especially grown in plastic greenhouse on Jeju island, Korea. Binomial sampling plan was developed using the relationship between infested proportion of twig with less than T scales (pT) and mean density per twig (m) according to the empirical model ln(m)=α+βln(-ln(1-pT)). T was defined as tally threshold and set to 1, 2, 3, 4 and 5 scales per twig in this study. T=3 was the best tally threshold for estimating densities of CMB based on the precision of the model. Binomial model with T=3 provided reliable predictions of mean densities of CMB observed on commercial citrus orchards. The obtaining model was evaluated by resampling validation of Wald's sequential binomial plan and by fit at 95% confidence intervals for independent collected data sets. Binomial sampling program for decision-making of CMB population level was obtained at the action threshold 0.10, proportion of twig infested with more than 3 scales.